The story takes place in Japan. The year is 2030 and Earth has been completely overrun by a viral disease named "Gibia" that turns infected people into various different monsters, based on their age, sex, and race. A samurai and a ninja from the early Edo period travel together through time and arrive in a ruined Japan to aid a professor working on a cure for the virus. Together, they fight countless Gibia monsters, outlaws, and other fierce foes on their journey to save mankind.

GA: Geijutsuka Art Design Class OVA. "I Want to Draw the Blue Sky"

Unaired episode 13 included with the fifth Blu-ray and DVD volume.

In most ordinary high schools, many stories and rumors float around—some scandalous, some happy and some...more macabre. One such example is of monsters lurking in an abandoned mansion outside of town. Such tales, however, prove too tempting to resist for Hiroshi and his friends Mika, Takeshi, and Takurou. They decide to brave the rumored dangers in order to investigate the manor and complete a test of courage. Each of them approaches the mansion with an overwhelming sense of dread. And when they enter, they come upon a blue monster named Ao Oni who attacks them. As Hiroshi and his friends try to solve the various puzzles in the mansion and escape their new blue nemesis, they find themselves meeting several horrible endings as they fail miserably. [Written by MAL Rewrite]