
Totally agree but even if Riku is a sociopath he keeps to himself and isn't directly mean to other people and he did asked Fuku not to be too hard on Shou. The fact that he doesn't feel any compassion, remorse or feelings of any kind is for me not worse than being able to feel things like Fuku and still act horribly towards others.
But sure that guy has some serious issues

I think at this point they are both equally as bad as the other and equally guilty. It's just a matter of ethics? If you knew someone was going to, let's say, murder someone and you knew you could stop them but let them do it regardless (Even instigated the act), then who's guilty? The murderer or you? To me it's both. The murderer committed the act, but your silence aided them. Does that make sense?
As for Fuku, [I really don't think I'll be able to explain what I'm thinking properly cause even I don't know how to word it right, but it's there so forgive me LOL] I feel like it's a case of very fked up emotional immaturity or inexperience. Like, if you think about it, that guy has only adopted mannerisms he has seen others react to as "desirable". He knows how to "carry" and present himself to society. He's in no ways stupid, but when it comes to his own emotions and how to act as a result of them, he's no less than a manifestation of all the worst traits of a child. He's probably never really had a chance to interact properly with others since he was born. As such, doesn't understand basic morals nor has he adopted a sense of what's "right" and what's "wrong. He likes Shou, so he thinks how can I get him? Obviously, the easiest way is to isolate him. It seems right because it's easy, but Fuku is now realizing it isn't. It's like how a child learns by experimenting, I suppose? My point is: Fuku has probably like adopted all the traits of a sociopath because that's how he's grown up until now, but he isn't actually one? (Oh god now I sound like I'm defending the a**hole)
Is no one going to talk about Riku (was that their name?) and how they're clearly enjoying this whole situation. If y'all going to start pointing fingers and screaming 'psychopath/sociopath' and what not, then what does that make of Riku LOL? They clearly knew this would all happen to Shou should they interfere like they did (all cause, what? Fuku rejected them?) but they did it out of spite regardless since the situation would amuse them. Fuku is rather "mentally unstable", than a sociopath? I would call him emotionally immature and although I can't pinpoint it right now, the real sociopath in this story is Riku, who has pointed out that sociopath/psychopaths don't show "remorse" and guess who's not showing remorse regardless of what Shou went through cause of their immature jealousy... Is this even a salon or a mental hospital at this point Σ(  ̄□ ̄||) my precious boy Shou needs to get the hell away from all this smh