Chapter Text
Atsushi had a strict sleeping schedule. He always felt sleepy by nine and woke up at five. At the orphanage, he’d only had a few minutes to get dressed and brush his teeth before he had to clean until his fingers bled.
Now he had plenty of time before he had to go to work at seven. He read, cooked breakfast for him and Kyouka, and… Well there wasn’t really much else to do but that was alright because soon he would have work.
Then the insomnia hit. Once, maybe twice a month, he just couldn’t go to sleep no matter what he tried. Instead, he spent the night staring up at the dark ceiling of his closet feeling bored and antsy, as if he were caged in.
He had taken to carefully opening the closet door, doing his best not to wake Kyouka as he went outside. He felt as if he were doing something forbidden by taking those walks, even though he didn’t have a curfew and was doing nothing wrong by walking around. He always returned by five anyways, to get started with his usual routine, though by then the exhaustion would finally hit and he’d stumble through the day trying not to show it.
He never told anyone about this issue as he didn’t think it was a big deal. Everyone had trouble falling asleep sometimes, right? There was no reason to bother them about something so small.
Then on one of those nights, he forgot his phone as he went on his usual walk. That usually wouldn’t be an issue, except that same night Kyouka woke up to use the bathroom and sensed something off. When she came back out, she noticed the closet door was cracked open rather than completely closed and when she carefully pushed it aside, it was empty.
She did not immediately panic. She called him. She heard a phone buzz and found it next to his pillow.
Then she panicked and called Dazai.
Everyone in the dorms went out looking for him, thinking he’d been kidnapped again by some other unknown enemy. Naturally, Dazai was the first one to find him walking through a park.
“I’m sorry for waking you all up,” Atsushi said once they were all reunited and he had explained he was just taking a night time stroll.
“You didn’t wake us up, that was Kyouka-chan,” Kenji helpfully pointed out.
She glared at him.
“She wouldn’t have had to do that if I hadn’t left, so I’m sorry.”
“It’s fine, just leave a note next time,” Kyouka said.
He nodded and kept his head down as they walked back, trying to think of a way to make it up to them. Maybe he should bake them something? A cake? Cookies?
Dazai slung an arm around his shoulders, jolting him out of his thoughts.
“You know, you looked pretty comfortable out there. Do you go out here a lot?”
“Not really, just whenever I can’t sleep.”
He hummed. “And how often would you say that is?”
“It’s only like once or twice a month, so it’s really not a big deal,” Atsushi said hurriedly.
“Is that so?” Dazai asked, his teasing lilt sounding a little more serious than usual.
“Uh, yeah.”
Dazai hummed again, looking up at the full moon on their walk back.
A few days later, when he had recovered from the sleep deprivation, Atsushi settled on a chocolate cake with vanilla frosting that was decorated with cookie crumbs on the sides.
Conveniently, Dazai decided to walk into work just in time for lunch, which was also when they planned to cut the cake.
“You didn’t have to bake this cake for us,” Tanizaki began.
“Yes he did,” Ranpo said, already on his second piece.
“What he means is that you don’t need to make anything up. We chose to look for you,” he continued.
“I know, but it was thanks to me we were all tired the next day. It was lucky that there weren’t any cases. I just really wanted to make the cake,” Atsushi explained. Though really, it was more like he needed to make that cake, needed to do something to make it up to them.
“And we’re all thankful for that Atsushi-kun,” Dazai sang as he and Kunikida walked in.
They were both a little late to the lunch party as one was busy yelling at the other about skipping work.
“You’re not getting any cake Dazai, not when you’re FIVE hours late!”
“But Kunikida, I was busy! I was researching something very important that could help the agency.”
“And what’s that?”
In answer, Dazai pulled out a book… About tigers. It did look as if it had been studied thoroughly, with creases on the spine and tabs sticking out of it almost every other page. He flipped it open to one page titled “Night Time Activities”.
“According to my research, it seems tigers are nocturnal creatures. They do most of their hunting at night and sleep during the day. The tiger must be the reason behind Atsushi-kun’s insomnia.”
“But it doesn’t happen every night, only once a month,” Atsushi argued.
“And does that once a month happen to coincide with the full moon?” Dazai asked knowingly.
He was about to say no, when he realized it did. His walks were always illuminated rather well because the moon was always full on those nights.
“So, the tiger is causing his insomnia,” Kyouka concluded.
“Wait, I thought the moon phase didn’t have anything to do with his transformations,” Tanizaki said.
“It doesn’t really. Before, I transformed no matter what phase the moon was in. Now I can control it, but the tiger always seems stronger when the moon is full. It’s like there’s a door keeping it out and usually that works, but when it’s a full moon, suddenly the tiger is body slamming it and the wood is bending.”
“Well, now that we know what’s causing this behavior, we can stop it. Getting a good night’s sleep is important. Yosano-sensei?” Kunikida gestured to the woman.
Atsushi took a step back on instinct but she grabbed his arm to keep him from running away.
“Of course. I would be glad to find something to treat this, though it would have been nice if I were told sooner,” she added, with a meaningful glance.
“It only happened once a month, so I didn’t really think I needed to mention it.”
“One night of bad sleep is normal. A night of bad sleep occurring in a pattern is suspicious. Now come on, I think I have some sleeping pills you can try,” she said, dragging him away before he could finish his cake.
He decided to try the pills that night since he could tell the moon was full enough that it would be a two night of bad sleep month. Just moments after taking three of them, his head hit the pillow in a dead sleep.
It was a bigger dose than what would be given to a normal person, but he delightedly reported their effects to Yosano the next morning.
“You think the tiger is going to have any other effects on him?” Kunikida asked.
“Maybe. All we can really do is keep an eye on him and try to help him,” Dazai shrugged, watching the other make a note.
He thought of the notebook hidden in his apartment, full of ideas to help with any unwanted tiger behavior. The best thing to do would be to take preventive measures, but that would be boring. Instead, he’d watch as nature took it’s course, while ensuring no one would get too hurt in the fun chaos that he was sure would soon begin.