"Koakuma Heaven" (小悪魔ヘヴン, Koakuma Hevun) is the thirty-first single by Japanese musical artist Gackt, released on June 10, 2009. This single was the first of four singles of the countdown to Gackt's 10th anniversary as a solo artist. This single was titled The 1st Heaven. Each of the countdown singles were scheduled to be released within a week of each other. The second song on the single, "My Father's Day" was written in memory of Gackt's Fūrin Kazan co-actor and close friend, Ken Ogata.