Orihara Kouhei returns to his town after a long disappearance to fullfil the promises he made to several girls in his childhood. He suffered from memory loss, and carries a tragic past. An strange ambience surrounds the OVA...It's almost like a dream, like memories from the past trying to come together in one piece but without being able to...

The story takes place in the land of Amber Ground, a place of perpetual night only partially illuminated by an artificial sun. Lag Seeing works as a "Letter Bee" (delivery boy) at the "Bee Hive" (a delivery service), with his Dingo, Niche, and her "pet," Steak, traveling with him. He is entrusted with the "hearts" of the everyone in Amber Ground to deliver their packages.

Around the the 37th year of the Meiji Era (1904), in the midst of the Russo-Japanese war, the small Japanese army, in need of assistance, uses its special flying (thanks to a benevolent demon) ship, the Amanohara, to attack Russia's major base at Port Arthur (Lushun). Umakai Shintaro, a Russian diplomat originally from Japan, defects and goes to Sapporo to teach at a girls academy. However, that girls academy is not typical—it is on board the Amanohara, and the five girls Shintaro teaches are known as the Raimu Unit—girls with the ability to summon powerful beings to fight for them. Shintaro eventually becomes their teacher and general in battle, and so the six embark on a weird and excessively erotic journey, as Shintaro helps the girls overcome their weaknesses, become stronger for the final stand at Lushun, and also understand the motives of the "Russian Spiritual Corps" that assist the opponent, which, unfortunately, has one member whom Shintaro knew well...

Legend says that centuries ago, a colossal spider ravaged Tokyo. Resistance was futile, as none could quell the havoc wrought upon the city by the beast. Fortunately, one man—the legendary exorcist—stopped the devastation. Using his divine powers, he sealed the monster away and the world has enjoyed peace ever since. Mizuki Henmi is an adolescent girl who is acquainted with Shu Suzuri, a dull young man who runs an old Japanese bookstore. During a routine visit to his store, Mizuki learns of a mysterious and valuable book that Shu is planning to sell. Unfortunately, the unrestrained Mizuki handles the book roughly, breaking the seal that kept it shut and revealing an odd entity—a cute spider. Wasurenagumo tells the story of Mizuki, Shu, and their seemingly harmless spider. However, ominous winds begin blowing. While Shu is infatued with his arachnid friend, Mizuki becomes wary of its every move…