Ryuuichi Kaizu, intelligent, ambitious, and dedicated, but at the same time cunning and immoral young student receives present from girl Emi Naito, who comes from wealthy family. Realizing that being in relationship with her can help him reach his goals, he decides to make her his, without her even being aware she is just another woman he is using.

An OVA produced to celebrate the 20th anniversary of Watase Seizou's Heart Cocktail manga. (Source: AniDB)

Now that Adol Christen has saved the land of Esteria from the evil priest Dark Fact, Adol and the two priestesses travel to the floating land of Ys, where evil has an even greater influence on the people and no one has hope. The future of Ys falls to Adol, heir to the powers of the priests and the only one who can show the people of Ys the truth about their world. But, as Adol's power grows, he may be the one who will save Ys—or destroy it.

Tsuki ni Naku will take the story content from volume 11 of the manga, which features a visit to a onsen by the members of the Hiizumi Life Councelling Office, while the town's police force have to deal with a new youkai-hunter threat. This OVA is bundled with the limited edition of the manga (14th, 15th, and 16th).