I'm looking for a manga that is about a student that forgets about his friend and roommate and think he is invisible and is a ghost because the roommate tried to rape him. Its only after a while that he realize that the person is real, he just forgot about him because of the incident. The manga also contains another story which has the same characters but focusing on two different characters. The story is about a guy's cousin who comes to live with him that has a mysterious 'vampire power' to kill plants. Turns out its just him mood killing them. Anyway the guy feels frustrated that the cousin has changed since their childhood days and doesn't know why. There are a few more chaps that continue the story of the first one but thats all i can remember. Its either yaoi or shounen ai.
Thanks in advance ^^

Koisuru Ikimono