But seriously though why does he hate the concept of comradery and colleagues.
Think about what has he gone through ever since coming to this unfamiliar world...
Also I also side with him not wanting to go and help jun, In the first place the reason this co called colleages is because of their own personal benefits, one is for revenge, one for reclaiming her lost world, and the other is for his organization. Really, from the start, there is no friendship, or comradarie or whatever the fuck it is. Since helping Jun, go save his comrades who's a part of an organization, we still dont have a clue if their good or not, since helping him will have no benefit for him whatsoever.
