3.985 out of 5 from 70 votes
Daikichi's grandfather dies, leaving behind a young daughter named Rin. However, as most of the family is embarrassed at the idea of a 79-year-old man having a six-year-old child, they can't seem to figure out what to do with her. Disgusted by this behavior, Daikichi decides to take care of her himself, but he's a bachelor, has no idea how to raise a child, and doesn't even like kids! Now, Daikichi must do the normal things a parent does such as enroll her in school, buy her clothing and teach her about the life and world around her. But more importantly, he must also help her deal with her father's death and decide whether or not she should try to find her mother. Together, the two begin their unlikely relationship as father and daughter.
Both of these series are about a young man suddenly looking after a young child. The child in both stories is self reliant (often more so than the young man) and quite shy at first, but the young man helps bring them out of their shell (while learning more about himself & about life in the process).
Each of these mangas is about a young man looking after a young boy. In Flat, the man is babysitting someone else's child. In Gakuen Babysitters, the young man is babysitting the children of many other people, plus trying to raise his own baby brother.
Each of these mangas is about a young adult suddenly being asked to look after a child who is not their own. The adult is reluctant at first, but grows more attached to the child as they spend more time together. The children also become quite attached to, and dependant on, their new caretakers.