Lime-iro Senkitan

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...