ok with this im 100% sure i dont want anyone to get together, like everyone should be single at the end:
goto? nope, manipulative and a hypocrite, she legit wants to send an abused teen to her home coz its bad to wrong away...fuck no
sayu? nope, she's a good kid, but she needs a proper home more than anything, she doesnt need romance
kouhai? nope, it feels like since she knows she already lost she's trying to stirr up some shit, like make him doubt his ''love'' (even if its a shallow attraction), and it looks like she projecting some shit of her past on him, fuck that
the mc? does he likes the megatits or her? honestly i forgot what else he saw on her, also his moral compass is too rigid, hes so confidant about not developing feelings for sayu that hes blinding himself, so the moment he realizes he already developed feelings for her his fucking mind its gonna collapse
fuck romance in this particular case