Synopsis
After their parents are killed in a plane crash, Ryuuichi and his younger brother Kotarou are taken in by Youko Morinomiya, the stern chairwoman of an elite academy whose son and daughter-in-law died in the same accident. The Chairwoman makes it clear that in exchange for being their legal guardians, Ryuuichi must work outside of class hours at the school's daycare, where Kotarou will stay during the day.

The series tells the story of the daycare children's antics, as well as how the two brothers adapt to their new lives.

(Source: Gakuen Babysitters Wiki)