Asteonome's nickname is Theo. He is a Siren who can seduce people with his singing and voice to get things what he wants. But it is forbidden to use this ability. When he touches water he'll turn into his Siren form and it will grow a fish tail so he can swim very fast and seduce people. When he is in his siren form, he will try to seduce the people near him. He is a very quiet student and dismissive. He likes reading and writing. He barely talks or just answers shortly.