Help identify a manga / anime / game / comic , these are the clues :
- Protagonist suffered some kind of head injury during an accident
- He saw humans including his own friends look like monsters
- He saw his environment (house , wall , chair , floor) looked like a bloody (red) organic disgusting mess
- Suddenly there a little girl that appeared normal and only this girl looked normal.
- he fell in love with the girl , and he become abhorent of his own friends due to their appearance to him.
- the girl in reality is the monster , who looked not even humanoid but some kind of moving flesh with tentacles ..