Context: Isshiki Makoto 一色誠 asks Togashi Yuuta 富樫勇太 about his relationship with a (troublesome) girl. Yuuta firmly denies having any relationship with her at all, prompting Makoto to question his sexuality.
nanda, omae moshikashite... なんだ、お前もしかして・・・ What is [it], could it be that you [are]...