AKA Yozakura-san Chi no Daisakusen
Taiyô Asano, is socially inept after his family's death, can only interact with Mutsumi Yozakura. Mutsumi's brother after injuring her, targets Taiyô. To survive, Taiyô must marry Mutsumi, join the family, and become a spy to protect her.
Note: This show is in Japanese Language but with hardcoded English Subtitles.