Umm... I don't think he's a bad guy but a little ignorant of the truth about his so called crush that is missing/dead, lets me guess he probably has family problems at home and the one person that payed him any attention was karagaki the person he fell in love with, now that she's dead and the second a older dark haired mysterious onee-san shows up and pays him a little attention, he's off to the next girl which is probably an alien like Tamachi.