In the heart of the tale lies the legend of Nanana's treasure, a ghostly figure once a stunning yet idle girl. Juugo, a boy abandoned by his father, finds himself exiled to a high school situated on the 'Special Student Zone,' an artificial isle. Struggling with a meager monthly allowance of 40,000 yen, Juugo settles into a budget-friendly apartment haunted by Nanana. Together with fellow members of the school's adventure club, Juugo embarks on a quest known as the 'treasure hunt royale' across the island in pursuit of the Nanana Collection, a coveted relic veiled in enigmatic powers.