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)
