Tsukuyomi: Moon Phase (月詠) is a Japanese manga series by Keitarō Arima. The manga was serialized in the monthly manga magazine Comic Gum from March 2000 to March 27, 2008. The series spanned sixteen manga volumes that were published by Wani Books in Japan. The manga series was later adapted into a 25 episode anime television series by Shaft, and aired on TV Tokyo from October 5, 2004, to March 29, 2005. An additional OVA episode dubbed "Episode 26" was later released only on DVD on February 22, 2006. Moon Phase is about a young vampire girl named Hazuki and a Japanese freelance photographer Kouhei Morioka whom Hazuki attempts to make into her servant.
While there are differences in adaptations, the main theme of Kouhei protecting Hazuki from harm is present in both. The OVA storyline though has very little to do with the original series outside of having some of the same characters, and has a completely different storyline which does not fit into anything which came before it. Tokyopop published an English-language version of the manga but stopped at volume 12 due to the company shutting down its North American publishing division which left the series unfinished. For the anime, Funimation released an English-language version under the name Moon Phase.