Archive of Our Own ^beta

Chapter Text

Ninja Registration Numbers, or Ninja IDs. I know, the most exciting of topics. All the hidden villages are supposed to have them, though for villages other than the Hidden Leaf, we have very little data. These numbers are one of those tiny details Kishimoto threw in, but which have a certain relative significance.

An ID number should roughly match with a person's age and when they graduated. The lower the number, the older they are. However, like all things with the Naruto series, there are some wrinkles in the data that need to be ironed out, large leaps which do not make sense, in addition to data that just doesn't fit the story.

Before I go any further, I want to say that this analysis is directly tied to my timeline project, the first part of this world building series. Therefore, there will be some fanon changes which resulted from me trying to straighten out said timeline. In fact, I will be updating the timeline based on the work I do here.

Before I dig into the numbers (and probably make all of your heads spin), I'd like to go over some basic concepts I included in the timeline project, as they make the process of analysis easier.

The BKY/KY System

This is a system of absolute years that I applied to the Naruto timeline (using Seelentau's timeline as a base). Normally, fans have to measure time relative to Naruto birth, which is inconvenient for a few reasons. I decided to measure time based on the establishment of the hidden village system, starting with the founding of Konoha.

Other fans have used this same idea under different names, but for me, I used BKY/KY, Before Kage Year and Kage Year. What's important is that Part 1 of the Naruto series is set in 63 KY, or 13 years after Naruto's birth, and Part 2, or Shippuden, is set in 66 KY. Basically, take any KY/BYY number I give and subtract 50 from it to make it relative to Naruto's birth year. 

Standardized Graduation Day

In Seelentau's timeline, a lot of characters are listed as graduating "at the earliest [X day]" of a given year, because that's when their birthday is. It's a good way to put down the data on the timeline, but it doesn't change that it's chaotic.

One way to help tame this chaos is to create a standard graduation day, a day when all students of a given year graduate. Every real world school has one, and logically, so would the Academy. Granted, in the real world that day fluctuates based on the day of the week, but that can't be accounted for in the Naruto series, so instead, we must stick with a single day.

For my work, I chose that day as January 22nd. It's the day Seelentau set for the Rookie Nine to graduate, since they all graduated at 12 and Shino's birthday was the next day. A January date works well in my opinion, but as I discussed at length in the timeline (See Chapter 3, Section #51), it could be moved to March 22nd, depending on your own writing.

Either way, standardizing the graduation day like this requires shifting the data slightly, as students will not graduate until the next year.

This date only applies to the Leaf Academy, however. It could apply to the others as well, but given that we're talking about other countries, with their own cultural variations, they could also have their own school schedules, so I am less inclined to declare the same graduation day for them.

Certain Characters' Data Has Been Altered

The age, death age, and graduation data for characters like Dan Kato and Might Duy was altered. This was because the data given for these characters caused a great deal of problems for the timeline and the overall narrative of Naruto.

Also, Raido Namiashi's ID was changed because he was paired with Asuma and Kurenai for the Chunin Exams in a flashback. While it could have been an uneven pairing, I decided to make it so they were on the same genin squad.

Plus, with the way the data stands, it would mean Raido was a genin for 4-5 years already, as he is about four years older than they are, except in the flashback, he does not look significantly older than anyone else.

Other characters had their data tweaked as necessary, like Genma and Ebisu's ages. Kakashi still graduated at the age he's supposed to, but was delayed in joining a team, so that's why there is still the discrepancy with the rest of his team and their IDs. See the timeline for more on that. 

The Academy's Maximum Capacity

This is something I discussed in the timeline. What is the academy's maximum student capacity? We know the Kiri Academy can hold over a hundred students, because Zabuza killed a hundred. The Leaf Academy should be that big at least. In canon, we hear that 27 students graduated from the academy at the start of the series. However, that number is the exact capacity for Irkua's classroom.

If you look at the classroom, the seats are tiered, with three tiers, three rows of long desks per tier, and three students per desk. 3x3x3=27. Also, as pointed out in the fanfic Drops of Sunshine, if ninja graduation numbers were always that low, the ninja population would have already died out. Let's not even think about raising large armies at that rate. Remember, Iwa lost a thousand shinobi in the third war.

There must have been more than 27 graduates, and more than 27 students. We don't see these students at all, true, but in this case, we should be forgiving to the writer, as they do need to try and keep the number of characters under control. Logic tells us that the academy must have more than one homeroom class, and each class can have up to 27 students.

But how many homerooms are there? With that information, we can also determine the academy's overall maximum student capacity, or how many students could make up a year's graduating class. Attendance at the academy is voluntary, even if it may be socially encouraged, so the academy may have low attendance years, to be fair, but we can still determine an upper limit.

My best guess was 297, or, to go for a more rounded number, 300. Since each classroom can hold 27 students, the academy's maximum capacity, whatever you choose it to be, must be divisible by 27. Given the size of the academy, 300 students seemed a reasonable guess, making it so it hosts up to 11 homeroom at one time, with space for one additional team.

Other Sources of Ninja: Immigration And Defectors

While we usually think of an academy as the main source of a hidden village's shinobi forces, and it is, we must also consider the secondary source of new forces: Immigration. Imagine this scenario. A shinobi in Country A decides he doesn't like working for Country A. Country A stinks. He's much rather work for Country B. So, he defects from Country A and goes to Country B, and asks for a job.

Country B is, naturally, skeptical at first, and there would logically be a probation period where our hypothetical shinobi is checked out in case he's a spy, but everything goes smoothly, and our shinobi is accepted into Country B's forces.

This has happened in canon, sort of. The character Kawaki in Naruto did not go to the Academy, but was made an official Leaf ninja. I could also argue that logically, Shizune didn't go to the Academy, either, and her graduation data is bunk. The point is that these characters, upon being made Leaf shinobi, would have been given Leaf IDs. Why? Because IDs are a form of record keeping.

Even the founders of the Leaf Village, people like Hashirama and Tobirama, would have been given ID numbers retroactively. Madara Uchiha, on the other hand, would not, if we presume the ID system was implemented with the creation of the training institution, as he left before it was built.

Defecting shinobi may not be able to close some of the huge gaps between certain character IDs (Like Ebisu), but it is a source for shinobi that shouldn't be forgotten.

Graduating vs. Passing the Instructor Test

Just a small notation here, because I want to make sure people understand this. When it comes to whether or not a character has a ninja ID, passing or failing the jonin instructor test does not matter. That is a canon fact. Once a student passes the academy's final exam, they are considered a genin and registered with the system. Whether their assigned squad fails the test set down by their jonin instructor is a totally separate matter.

The Raw Data

Here is the "raw" data to start with. It's not entirely raw, as this set already includes the tweaks I made to various characters like Raido, Shizune, Dan, Duy, etc, as mentioned previously. Also, while Narutopedia lists Menma Namikaze in their ID table, I will not include him, as he's just the doppelganger of Naruto, and it makes no difference here.

This data set will also account for the standardized graduation day, which will cause slight shifts. Fields labeled "NA" mean "Not applicable". In other words, there is no canon data to work with.

Table 1: (Mostly) Raw Data

I know, it's a lot. For now, look at the last column there. That calculates the difference between an ID number and the one in the previous row. As you can see, there are some rather large gaps. I've taken the liberty of bolding the largest of them, as well as one particular low point.

From here, let's go through every part of the data, investigate each jump, and also see about filling in data. Also note that Shizune's ID is a new one I gave her, and is open to change as needed.

First Class--> Sannin

The first large gap comes from the IDs of Homura Mitokado, and Orochimaru, the difference being 2,007 points. Homura graduated in year 10, while Orochimaru and the rest of the Sannin graduated in 19 KY. If we presume that the Academy has a maximum capacity of 300 students, then with a difference in graduation years of 9, 9x300=2700.

Now, it is perfectly logical that the academy might not have been big enough to accommodate 300 students at the very beginning. But even with that in mind, there's more than enough room that this gap in ID numbers doesn't pose a real problem.

Sannin--> Dan's Group

The next large gap comes between Tsunade's ID and Dan Kato's, a different of 671 points. There is a two year difference between their graduation years, so that could account for up to 600 points of that gap. As for the remaining 71, those could be accounted for between the other IDs in Tsunade's group. So, this gap, too, is not problematic. There's more than enough space to make it work. 

Dan's Group--> Fugaku Uchiha, Filling in Fugaku's Data

The next big jump is between Might Duy and Fugaku Uchiha, where the IDs jump 1,085 points. The issue here is that we don't have any information on what age Fugaku graduated. So, the best way forward is to play around with the data, try out some numbers, and see if this gap can be explained without having to alter the IDs themselves.

Fugaku was born in 17 KY. This would have been during the First Shinobi World War. Genin were not thrown in this war, but it's important to have context. Since the last two characters graduated at 10 years old, let's try 10.

If he was 10, and his birthday is in August, then he would have graduated on January 22nd, 28 KY. If that's the case, there's a seven year gap between his graduation year and Might Duy's. 7x300 = 2100. That's more than enough to cover the gap. Let's also update the table with this new data.

Table 2: Fugaku Uchiha's Data Filled In

The Hyuga Twins and Nono Yakushi

Another large gap presents itself between Fugaku Uchiha and Hiashi Hyuga, one of 1,073 points, and once again, there's no data to draw from. The Hyuga twins were born in 21 KY, during the peace period between Shinobi World Wars 1 and 2. They were not really in a hurry to graduate. Let's start with a graduation age of...12.

Given their birthday of January 8th, that would make their graduation year 33 KY. That's a five year gap between them and Fugaku. 5x300=1500. That's more than enough time to close the gap.

Another character of interest is Nono Yakushi. Her ID is only 40 points different than that of Hizashi, suggesting either she was in the same graduating class, or the one right after. Now, her birth year is 26 KY, five years younger than the twins. In order for her to be in the same graduating class as the twins, she'd have to graduate at 6. At maximum, she'd graduate at 7 years old.

While we do not know much about Nono, other than she knew medical ninjutsu and was brought into Root, this data would suggest she was one of Konoha's prodigies, up there with Kakashi, Itachi, and the like. For me, I'm going to place her graduation age at 6, just to put her in the same class as the twins.

Table 3: Hyuga Twins and Nono's Data Filled In

Mikoto Uchiha, Nawaki Senju, Shibi Aburame, And Ino-Shika-Cho

This group doesn't contain any large gaps, but it does contain a surprising shortage. Mikoto Uchiha and Nawaki Senju have IDs that differ by only two points. This means they were in the same class, or that Mikoto was one of the last IDs assigned, and Nawaki was in the very next graduating class.

Nawaki died at age 12. In my timeline work, I set his birth year as 24 KY, giving him a 12 year age gap with his sister Tsunade, a reasonable difference between the two. I also ended up setting his death to 36 KY, which is more or less what canon would dictate, anyway.

We also know that Nawaki died the day after he turned 12. Having him die when he's still a genin, perhaps in the same year he graduated, plays well into Naruto's overall narrative, adding one additional layer to the tragedy. This would place his graduation year to 36 KY, and his graduation age to 11. If we also make it so that he and Mikoto were in adjacent graduating classes, that would make Mikoto's graduation year 35 KY, and her graduation age also 11.

Then there's Shibi Aburame, whose ID is only 130 points away from Nawaki's. This puts him well in range of being in Nawaki's graduating class. If so, he would have also graduated at age 11, which seems reasonable. After him, there's the Ino-Shika-Cho team who were most definitely in the same class, because they were on the same genin team. Their IDs differ from Shibi's by 10-12 points. But what age did they graduate at?

The Ino-Shika-Cho group were born in 25 KY. They graduated with, or just after, Shibi, who himself had to graduate with Nawaki, or just after. So, this would suggest they graduated in 36 KY with both Nawaki and Shibi. This placement would have the effect of having all three members of Ino-Shika-Cho graduate at age 10, which is symbolically appropriate, given that their children were Team Ten.

Table 4: Mikoto, Nawaki, Shibi, and Ino-Shika-Cho Data Filled In

While all these decisions are good, there's one little problem: The difference between Nono's ID number and Mikoto's is 148 points. If you place Nono's graduation year as 33, and Mikoto's as 35, that's way too small a gap. It might be possible to make it work by moving Nono's graduation year to 34, however, this issue provides an opportunity to help deal with another further down the line.

The Great Minato Traffic Jam

When looking at character ID numbers, it has been remarked how odd Ebisu's ID is, how it's over 500 points above that of his team. That issue will certainly be addressed, but I think the bigger problem starts with Minato.

As you can see, the gap between his ID number and that of Inoichi Yamanaka is 1,018 points. And then his wife, who was born the same year as him, has her ID jump another 800 points. Tsume Inuzuka's ID only differs by 40, but then you get an even bigger jump with Yoshino Nara, who has the second biggest leap out of the entire data set, a whopping 1,741 points. After her is Kakashi (Replacing Raido, who has already been moved), with a gap of 629.

This part of the table has the biggest collection of gaps, and it all starts with Minato. Canon data would tell us Minato graduated in 36 KY. Shifting the Ino-Shika-Cho group back even a little doesn't really help, as that pushes against Shibi and Nawaki. It also doesn't resolve the huge leap with Kushina's ID number, or the other two jumps.

I am generally resistant to changing a character's ID number unless absolutely necesssary, but that appears to be the case. To fix this, let's try increasing the ID numbers, with said increase starting with Mikoto, and going through Inoichi. Let's also make that increase 400 points.

Table 5: Increase of 400

This helps, but does not entirely fix the problem. The gap between Inoichi and Minato's IDs is still 618. If we keep the data set up like this, the total difference in IDs between Nawaki, Shibi, Choza, Shikaku, Inoichi, Minato, and Kushina should be somewhere in 300.

I am including Kushina because she was born the same year, and what's to say she didn't gradutate at 10 as well? Tsume is a little younger, so despite how close her ID is to Kushina's, it's reasonable to say she graduated after this group.

So far the difference in digits is 130+10+1+1+618+800 =1,560. Since there should be a difference of 300, that means that, using Nawaki's ID as a starting point, the last ID in this class would be 6050. Give or take 1, if Nawaki was the second person registered in his year.

With that in mind, let's drop Minato's ID to only, let's say, 60 points different from Inoichi's, and make Kushina's ID about 6 points different from Minato's.

Table 6: Inoichi-Minato ID difference of 60, and Minato-Kushina difference of 6

This helps clear up the huge gaps with Minato, Kushina, and the whole 36 KY graduating class. 130+10+1+1+60+6=208. However, it does not clear up the next bunch in this traffic jam.

Tsume and Yoshino

The tremendous gap between these two is especially ridiculous when you realize that Yoshino has the higher ID number and yet, is a year younger than Tsume. First, let's start by creating some data to work with. Since 10-11 seems to work, we'll make that Tsume's graduation age. For Yoshino, it seems she could have gotten an earlier start, but she graduated after Tsume, so let's say she graduated at age 12.

Table 7: Testing Data for Tsume and Yoshino

As you can see, this gives Tsume a graudation year of 39, and Yoshino a graduation year of 40. 39 actually works quite well for Tsume, as far as cleaning up the mess, as this allows up to 900 students to be added to the roster. Unfortunatley, this won't solve the ever-compounding gap with Yoshino.

There is one other alternative to try, however, and that's to make alterations near the very beginning. As mentioned before, if we assume a maximum capacity of 300 for the academy, then the number of students between the first class and the Sannin is 2,700, while with Dan's group and Fugaku Uchiha, it's 2,100.

The gaps between those IDs are actually significantly low. My next experiment was a multi-step plan. To cut down on the number of tables, I'm simply going to lay out all the steps together, and then show the final result.

Step 1: Add 500 points to the Sannin-Dan-Duy group

Step 2: Add 900 points to the Fugaku-Hyuga twin-Nono group

Step 3: Add 1300 points to the Mikoto-Inoichi group

Step 4: Since Minato's original ID has now been outpaced, add 400 points to it, and leave Kushina's ID as the original, but change her graduation age to 11, and her graduation year to 37

Step 5: Try adding 500 to Tsume's ID

Table 8: Multi-Step Results

This brings the IDs closer together, until we once again arrive at Yoshino. The problem is that the numbering after her is still very high, so even if you lower her ID, you'd have to lower all the others. There's just no room to account for that kind of massive gap.

Since this area has proven to be so very frustrating, let's go back to the beginning and see if that can't provide an answer.

Reviewing the Beginning

Canon data says that the first academy class, which included Hiruzen and his fellow elders, graduated 10 years after the founding of the village. The first class was also made of only 36 students. That is incredibly low, but for a first class, we may be able to let that slide. Now, take a look at the IDs.

What's the difference between the lowest ID of this set of four (Koharu Utane's), and the highest (Homura Mitokado's)? 293-256=37.

...Yeah, I thought it was 36, too. But I did the math and it's 37, so Kishimoto goofed up there. Actually, it's worse, because if you make two lists, one starting at 1 and the other starting at 256, you'll realize entry 36 is 291. Kishimoto was off by two. Mathematical errors aside, the intent seems to be that Koharu was registered first, and Homura was registered last.

But look again at Koharu's ID. 256. It has been remarked on how some of the very old ninja do not have ID numbers, or not ones we know about, but as I have said, the purpose of ID numbers like this is record keeping.

It is therefore reasonable to think that, when the registration system was invented (let's say, the same year the first class graduated), that all the adult, active shinobi in the village would have been given an ID number as well, regardless of whether they went to said academy.

If Koharu was the first registered graduate, and canon data suggests she was, then that implies there were 255 other active shinobi already registered in the village. If that is not meant to be implied, then why did the numbering start at 256?

However, 255 active shinobi present 10 years after the founding of the Leaf Village is seems incredibly low. Far too low to be believable. This leads to one conclusion: The entire ID system needs to be overhauled from scratch in order to make it work the way it's supposed to.

First, let's get the basics out of the way by creating the number of shinobi active in the village in 10 KY. I asked for advice on the Naruto Fanfiction Discord server, since I am terrible at these kinds of estimates, and got a suggestion of 603. In fact, I'll take that a step further and make it 605.

If we use this number, that means the IDs of the very first class should start at 606. Let's also keep the canon factoid that the first class was only made of 36 graduates. The academy was only three years old by the time the first class graduated, and we can forgive the small size. But beyond that, let's say that the academy was built to it's full size, with a maximum capacity of 300 students.

For the first two years, we'd have a set of constants.

Table 9: The First Two Years

See those columns "Lower" and "Upper"? Those are, respectively, the lowest and highest possible ID numbers for that given graudating year. Beyond those first two, determining the boundaries for the rest of the years on the list, or any other year, can be expressed as a pair of formulas.

Yes, I know this isn't math class, but don't groan. These are very, very simple.

Lower ID Boundary = 642 + ( (Graduation Year-11) * 300)

Upper ID Boundary = 941 + ( (Graduation Year-11) * 300)

Got that? Good. With that out of the way, and because this is actually far too large to post in one chapter, I will use chapter 2 to go over the complete overhaul of the Leaf Village ID system, and from there, come up with data for the characters who are still missing it.