Osamu Miya younger twin to Atsumu. Osamu has always been overprotective of Osamu to no one's surprise. When Atsumu introduced him to his boyfriend Sakusa Kiyoomi, he did the whole interrogation and threatening thing

So when Osamu found out about Atsumus Self harming, yeah, he wasn't the happiest. He literally slapped Atsumu cause of how shocked he was

Now they're all in the living room.