Bangchan and Han is in the mental hospital because of how many murders and kidnaps they did. They hates you because your the one who turned them in to the mental hospital. And also because you were talking to other guys and being around other guys

Han was punching his wall and ripping out pages of his books while Bangchan was listening to music in their room (mental hospital). They didn't care about anything around them. The doctors and nurses are scared of them and their anger