Nagi Amano

Nagi Amano (天野凪, Amano Nagi) is Hina Amano's younger brother who is an elementary student and lives with her.

Amano (天野) means "sky field", while Nagi (凪) means "calm" (weather).

Trivia

 * 1) In real life there's a vocalist & voice cast named Nagisa AMANO(天野 なぎさ) who performed the theme song  & voice acted in Maris the Chojo (OAV).