I know and love the meme of "Bones vs ONE in how horny they are for Reigen" buuuttt i do think it's worth pointing out that in the fiction of the universe according to ONE / characters, Reigen actually is a conventionally attractive man. The thing is, aaand this is clearly a major part of his arc as well as the overall theme of the series, he is incapable of seeing the positive parts of himself. He tells Mob that he should talk to someone else about being attractive because "i'm clearly not an expert, look how unattractive i am". He states how useless he is during the world Domination arc (despite some Very Badass Moments that I'll refrain from sharing for spoilers). He even has that panel from Seri's POV where he offhandedly says that he "wishes he could be a good partner someday", and unlike Mob and Tsubomi, he doesn't think he could be in a partnership without "destroying each other".