Nanana's Buried Treasure

is a Japanese light novel series, written by Kazuma Ōtorino with art by Akaringo. A total of 12 volumes have been published by Enterbrain under their Famitsu Bunko label. A manga adaptation by Hitoshi Okuda began serialization in Enterbrain's Famitsu magazine in January 2012. An anime television series adaptation by A-1 Pictures aired from April 11, 2014 to June 20, 2014 for 11 episodes on Fuji TV's noitaminA block. Before the first light novel volume was published in January 2012, A-1 Pictures animated a promotional video that was streamed by Enterbrain on December 26, 2011, after the novel won the top prize at the 13th Enterbrain Entertainment Awards in September 2011.

Plot
On the "Special Student Zone" artificial island – Nanaejima, the story centers on a beautiful, optimistic, but NEET (not in education, employment or training) girl named Nanana Ryūgajō, who was mysteriously killed in her own apartment.

Ten years later, a boy named Juugo Yama was forced to transfer to a high school on the island. With only a certain budget to live on, Juugo chooses a low-rent apartment that happens to be haunted by the ghostly Nanana, who is bound to her former home and unable to move on. Juugo and members of the school's adventure club join a "treasure hunt royale" on the island for the Nanana Collection, treasures that possess mysterious powers.

Official

 * Official anime website (in Japanese)