A mysterious boy who entered the school without a recognizable talent. True to his serious image, he prefers to keep to himself and would prefer to avoid interacting with others. His true talent is revealed to be the Ultimate Lucky Student. It's also all but stated that Tachihaki was the victor of a previous killing game as he successfully killed someone and got away with it. Is quite rude, snarky, pessimistic and has a negative view of the world, but tries his best not to bring others down.