The Whovian's Favorite

I didn't realize how often i used this or how much other sites suck until Mangago went away

I can’t remember a manga’s name. It talks about a man which soul detaches from his body every night. To prove it to himself he decides to put a rose in a tube (?) outside his house, (when his soul wasn’t in his body) and to check it the day after or something like that lol. I also remember that he was used to listen to jazz music and the themes and the drawings were kinda “dark”. Thanks a lot~