Why yes his sister was a bitch to him but he hid in the house playing video games for ten years. So he's probably neurodiverse, guess what there's a lot of neurodiverse people out there that don't rape their sister simply because she's annoying. I'm sure he can talk to whatever they call health services over in Japan and his sister will be out of his way and then he can kill himself or even just get a job and chat up some on-line friends the rest of his life.
Degenerates like you belong on a cross.