Nanana's Buried Treasure

“I'm going to build a place where young people can challenge to reach any of their dreams!”
The 7 genius students, known as the GREAT 7, launched a project to construct an artificial island called Nanae Island to realize their leader, Nanana Ryugajo's peculiar idea. 12 years later, with a total population of 100,000 people with as much as 80% of those inhabitants being students, Nanae Island has successfully become prosperous as a special student zone. One of the island's newest residents was Jugo Yama--a high school student who had just transferred to the island after being disowned by his father.

One day, Jugo finds in his own apartment the earth-bound spirit of the late Nanana Ryugajo, who was murdered by someone 10 years ago! Jugo's plan of living alone was suddenly thwarted by this strange roommate.