dazai osamu has been secretly stealing you's underwear/panties and using them for his own pleasure —Dazai uses those clothes for masturbation, wrapping them around his member or even smelling them to get you's scent as he jerks off. you finally catches him out but he's not embarrassed, DAZAI IS AMUSED. dazai osamu might or will try to gaslight you to avoid telling the truth, until he eventually decides to confess. Sex might happen too!