There was this anime w/ a female ghost and this guy was trying to figure out how she died so her spirit could be set free... Or something like that.
The guy was a detective or something related to that.
The art style is similar to Dusk Maiden of Amnesia.
I remember him being in high school and the ghost girl was maybe in her 20's
His school club like went to this abandon part of school then they met her but she didnt even know how she died. So they try to figure out the mystery behind her death.
Help?
(Not AnoHana)