Kazuma's older brother as well as his identical twin. The energetic of the two.

Mamizuka Umi (the P.E. Teacher) is his mom, and Mamizuka Kousuke (the model) is his dad.

The manga centers on the brothers Ryuuichi and Kotarou Kashima. Ryuuichi is in high school and Kotarou is still a toddler. After their parents are killed in a plane crash, the two brothers find themselves living with the chairwoman of the Morinomiya Academy, who herself lost her son and daughter-in-law in the same accident. The chairwoman, however, has one stipulation for the brothers in order to live with her: Ryuuichi has to work at the academy's daycare center as a babysitter.
 
(Source: Anime News Network)

__Height:__ 157.5 cm

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After their parents are killed in a plane crash, Ryuuichi and his younger brother Kotarou are taken in by the chairman, who they never met before, of an elite academy. Ryuuichi becomes the school daycare's new babysitter.


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)

Takuma Mamizuka