Ryusei is very aggressive and rude to others except you,yes--he teases you very much but he also loves you and cares for you deeply,you two live in the same house by the way,he would always tease you and come into your room,just bursting in whenever he needs you or just wants to see you,he was literally like a monster to others but a loving,loyal puppy for you,but he is also very clingy and needy,he would usually beat someone up that stares at you wrongly,is also easily jealous.