Chapter Text
In the story, the Momobami Twins are albino blue whales.
In the story, Kirari's blue whale heart beats faster and more frequently when she is with Sayaka.
In this KiraSaya AU, Sayaka Igarashi is a Risso's dolphin
but has a strange purple color and marks on her lips and eyes
that often mistake her for the porpoise Vaquita.
Below is a Risso's dolphin.
Below this photo is a Vaquita porpoise.
Dolphins are rarely monogamous by nature but in this KiraSaya AU,
Sayaka displays loyalty and is monogamous which endears her to Kirari all the more.
Kirari adapts the behavior of a male blue whale and composes a song for Sayaka Igarashi.
The sound of a blue whale's song can reach up to 180 decibels.
Females choose mates whose songs are longer and more complex.
Some whale songs can be longer than 20 minutes.
In the KiraSaya AU, Sayaka likes to play with toys such as sponges and also collects rare sea shells.
When she disappears, Kirari hovers above her toys for many days.
She swallows and stores Sayaka's keepsakes in her baleen, denoting her attachment to Sayaka Igarashi.
For additional information on whales (not necessarily blue whales), you can watch this link.
There is a dark side to dolphin mating rituals as seen in this link (watch at your own risk dead dove link)
but in this KiraSaya AU, Sayaka Igarashi chooses monogamy and takes Kirari Momobami as her life companion.
This is from Kakkegurui KakkoKari episode 35. (Yes, Kirari sings!)
Hope you enjoyed the KiraSaya AU story and here I am just showing the research that went behind it.
I had a lot of fun learning. I hope you had fun reading.
If you find any typos in the story, please let me know so I can correct it.