I feel Runa does say very mean things abt Ayumu too, but because Ayumu never really seemed to be truly bothered by it, I'm never really bothered by it too. Sure she gets mad and they bicker a lot, but if she was really bothered by it I don't think she'd keep laughing with Runa like that. So what I'm saying is I trust Ayumu lol, and Runa suffering is a pretty nice karma for him too lmaoo. That's my whole take on Runa's teasings.