Ryuugajou Nanana no Maizoukin

The story centers around the treasure of Nanana, a ghost who was once a beautiful but NEET (Not in Education, Employment or Training) girl.
A boy named Juugo was disowned by his father and forced to transfer to a high school on the "Special Student Zone," an artificial island. With only 40,000 yen a month to live on, Juugo chooses a low-rent apartment that happens to be haunted by Nanana. Juugo and members of the school's adventure club join a "treasure hunt royale" on the island for the Nanana Collection, a treasure that possesses a mysterious power.