Am I the only one who got Pillar Men vibes?
Also, well, 2 boys, 2 girls squad for now. Still hope it won't be a harem. And still a soft tsundere, she is not hitting him for being seen with other girl or baka-moment, but for leaving her alone with his new muscle bro
As for his powers: It seems he had 'something something sealed evil in can' in him, and it is a real source of his OP magic. Think of Jinchuriki from Naruto, this can be a similar case