Orphans Ryuichi and Kotaro are taken in by the chairwoman of Miyanomori Academy, on the condition that Ryuichi become a babysitter in the school's daycare. This daycare turns out to be full of young children just around Kotaro's age...

Ryuichi is in high school now. He takes the daycare gang around to see the school's clubs, which are recruiting. He also tries to get people to join the babysitter club, but it doesn't seem to be going very well...

Later, Ryuichi gets sick, and has to stay in bed. On the chairwoman's instruction, Kotaro works hard to try to make Ryuichi a special drink that will make him better.

Usada is home sick with a cold, so he asks Saikawa to serve as babysitter in his place. Saikawa is good at everything, but can he handle being a babysitter? Later, Ushimaru visits the daycare room for the first time at Inomata's invitation. She has a hard time dealing with little kids, and now she's surrounded by them!