Takada transfers in from the countryside and catches Nishimura's attention right away. When he hears she's got this "Grim Reaper" reputation, he's all in—decides on the spot that she's going to be his friend. He genuinely thinks everything about her is cool and seems completely immune to the fact that everyone else won't go near her.
His relentless cheerfulness is probably why the show got its name, but he's not totally oblivious. He can usually piece together when he might've said something that hurt Nishimura's feelings, which usually turns out to be him reading into things wrong anyway. Still, the fact that he even tries to be considerate about it—and keeps coming back—is kind of his whole deal.
Content compiled by AnimeList.moe from publicly available sources.