Taiyou starts as someone who can barely speak to another human being. By the end, he's willing to die for a family that isn't his, and the show makes you believe every inch of that transformation. The action is just window dressing, what actually kills you is watching a kid with nothing find people worth everything, then watching them find him back. The Yozakura family goes from "overprotective nightmare" to genuinely the most loyal found family in shonen, and you won't see it coming because the show pretends to be a comedy about annoying brothers for the first arc.

Taiyou Asano is a painfully shy high school student, and the only person he can really talk to is his childhood friend, Mutsumi Yozakura. Then he learns her secret: Mutsumi heads a family of spies with superhuman abilities, and her dangerously overprotective older brother Kyouichirou sees Taiyou as a threat to her. Because Yozakura family members are forbidden from killing one another, the way to keep both of them safe is for Taiyou and Mutsumi to marry. Once he joins the family, Taiyou has to train as a Yozakura spy to fend off the constant threats against Mutsumi and himself. The result mixes action, comedy and romance.