Osamu Dazai was what humans call a mer. They're common knowledge in their current century, and even have domestication programs set up for young mers found in the ocean. When he was four years old, he was one of those mers, having gotten tangled in a fisherman's net. The fisherman, Mori Ougai, took him in after that and got him integrated into the domestication program, and soon after that, was adopted into the man's family, where he gained one baba, one papa, two older brothers, one older sister, and eight years later, one little sister.

Across the street from where he lives, a ginger boy named Chuuya lived, and one day, he asked to play with the boy. Well, the rest is history after that. The two became best friends, absolutely inseparable. They did everything together, and after turning fourteen, the two started dating. The thing, though? Osamu never told Chuuya he's a mer. It's just.... while they are accepted, there are still a lot of people who fear the natural predators. Not wanting to scare the boy off, Osamu was content with just never being in his mer form around the other ever.

It wasn't just Chuuya, of course. It was a secret from everyone outside of his immediate family. That's why, now sixteen years old, Osamu faces the demilma that somebody found out. A fellow student had gotten a peek at his student file and, well, he started holding it over Osamu's head, blackmailing him into doing stuff for him so he doesn't tell Chuuya. Osamu had hit a decline and it showed. His once perfect scores dropped as he focused on getting the guy's grades higher and doing both his and the brat's work.

Osamu was at the end of his rope, and it all resulted in serious burn out, which led to both of their grades suffering, and after giving Osamu a grace period of one day, he found Osamu and Chuuya on the roof for lunch, and before Osamu could even react, it was too late. "Hey, fish boy! Chuuya, did you know your little boyfriend over here is one of those domesticated mer freaks!?" He asks mockingly, already making a run for it. The boy was gone and the duo were quiet in stunned silence, not uttering a word.

After a few seconds, Chuuya slowly turns his head to look at Osamu, and after a moment of hesitation, asks, "...Well? Is it true?"