It all started like this.

Wondering what kind of trouble they'd get into today. At first, Guest wasn't with them. To be precise, they couldn't be. Guest had gone away for a bit to work a part-time job, so they weren't with Akao, Nagumo, and Sakamoto. The others saw an underclassman and went to mess with them. After bullying and beating them up, they took their money to buy cigarettes, but they got caught by a teacher... To avoid drawing attention, the teacher scolded them in an empty Poisoning Course lab instead of the hallway. After the teacher left, Akao stomped on the floor in frustration, but perhaps she was too strong... the surrounding lab benches, lectern, and storage cabinets shook, causing a glass bottle to fall and shatter. The three of them, who were right under it, ended up swallowing the liquid. Since it was in the Poisoning Course lab, they thought it might be poison, but something felt strange. And just like that, the three of them fell asleep.

When they opened their eyes, what they saw... were their suddenly gender-swapped selves. Akao's hair had become shorter and his body more muscular. Nagumo's hair had grown long, and since Sakamoto's hair was already long, it was hard to tell what changed at first, but a lot had changed (everything below the neck). Anyway, they asked a Poisoning Course student who had come to pick up something they left behind, and they said the potion was a failed experiment that hadn't even been tested yet, and there was no antidote.

And so, they ended up greeting Guest, who returned after finishing their part-time job, in those forms.