No matter how closely he tries to stay connected, he cannot write everything. Even so, he writes. A one-year diary written by Ozaki Sekaikan, the frontman of Creephyp and an author, covering the period from age 40 to 41. The things he did not write are recorded in percentages so they are not treated as if they never existed. Ozaki Sekaikan, the frontman of the rock band CreepHyp and an author whose works have twice been nominated for the Akutagawa Prize, finally releases in book form the serialized work "Ozaki Sekaikan no Kakanakatta Koto Nikki," which recorded one year from December 25, 2024 to December 24, 2025 in the book and manga culture magazine "Da Vinci." At the end of each diary entry, the percentage of what was not written that day is shown as a "%," allowing readers to enjoy not only what was written in the diary, but also to imagine what was left unwritten. In this work, he teams up for the first time with popular picture book author and illustrator Yoshitake Shinsuke, and readers should also pay attention to the illustrations titled "Nikki Yonda Nikki," which respond to Ozaki's diary entries.