Why is Takumi so happy about having sex with his sister?

>>527794457
KG Tsubasa is so horny. Romance Route Tsubasa gets way more embarassed and nervous, and would probably take a while to actually put out. KG Tsubasa apparently fucked Takumi and went full yandere for him before the 100 days are even up. Weird disconnect I guess but I get it

>>527218580
they might fuck a lot, but surely Tsubasa wouldn't force him to do it raw?