Ryuichi and Kotaro are brothers who lost their parents in an airplane crash. They're taken in by the chairman of Morinomiya Academy, who lost her son and daughter-in-law in the same crash, on one condition: Ryuichi has to babysit the kids at the daycare room in the school! This room was opened to help the school's teachers who had kids to take care of, but it suffers from a lack of staff until Ryuichi becomes the first member of the babysitter club formed to solve that problem.

[Source: Crunchyroll]

In the OVA's story from the manga's ninth compiled book volume, Ryuuichi takes a break from the babysitter club in order to study for tests. Imitating Ryuuichi as he studies, Kotarou and friends practice writing. Ryuuichi wants to thank Saikawa, who helped him out during testing, and he nonchalantly tries to figure out what Saikawa likes. Ryuuichi makes curry for the chairwoman and Saikawa.

The OVA also includes a special "Snow White" segment based on a story from the manga's sixth volume. The chairwoman is the Queen, and Inomata is trapped in a castle doing nothing but studying as Snow White. Ryuuichi is the huntsman who takes her to the outside. The babies are the seven dwarfs, and they run into Usaida in the forest.

[Source: Anime News Network]