[Honoakari]

Spoiler for reply:

Neru used to be a very innocent, kind-hearted person. But after Kurono came along, her personality did a 180. Now, Neru no longer gives a f*** about Nero or the rest of the party - she only cares about Kurono. Can't blame Nero for being angry at him, I guess.

But aside from hating Kurono for "stealing" his imouto, Nero is also worried that Kurono might be using her for some selfish goals.

He thinks that there is something suspicious about Kurono's skyrocketing reputation... IIRC, at some point he was even speculating that Kurono might have some secret way of controlling people.

And he'll probably hate and suspect Kurono even more once he sees him together with Sariel, who killed one of his party members and who was supposed to be Kurono's biggest enemy...