Ikkyū Tensai no Kiwamete Fuhon'i na Nasuiri (壱級天災の極めて不本意な名推理? lit. Tensai Ikkyū's Extremely Brilliant Involuntary Deduction) or officially translated as Tensai's Reluctant Deduction is the side-story of Nanana's Buried Treasure, written by the same author and illustrator of the main story―Kazuma Ōtorino and Akaringo. The first volume was released on August 30, 2013 by Enterbrain's Famitsu Bunko. This story revolves around Tensai and D'arc's adventures.