I think in some weird fucked up way he got something out of being with Nagare he didn't get out of anyone else whether it was his determination, retaliation or naive resolve to push through because that framing was so shoujo-doki-doki I had to do a double take all that was missing was the "badum badum". I think Okaya wanted Nagare to stick around whether as a plaything or just a constant in his life this thing that wouldn't leave him no matter what he did to it. I think Okaya has some family issues or trauma I originally thought he bullied Nagare because he thought he was too happy and had too good of a family and he was jealous or thought Nagare was ungrateful.
One thing is for certain Nagare was special to Okaya.
Yeah i agree
Okaya really fucked up this one dawg
Maybe the main bully is actually gay but he's a psycho so that's why he bullied nagare. Idk