Fuuta-kun has never owned a cat before, but his younger sister, Pii-chan, moves into his house with the round gray cat Kyuruga. Inexperienced with cats, Fuuta-kun has no idea what to expect, and each night after he returns home is marked by odd and endearing surprises from his new pet.

Years ago, astronaut Byakuya left behind precious materials in the belief that his son, the scientifically-gifted Senkuu, would one day find them. In the present, the Kingdom of Science's Kohaku and Ginrou have infiltrated the harem of the Petrification Kingdom’s leader with the help of Amaryllis, a local girl. At first, their mission progresses without a hitch. Unfortunately, an error enacted by Kohaku and Ginrou leads Minister Ibara and the Island’s strongest warrior, Moz, to identify the intruding duo as enemies. Even worse, Moz tails Amaryllis when she returns to inform Senkuu of the news, discovering the scientist's secret hideout. However, Moz's agenda does not align with Ibara's—he wants to dethrone the minister and keep the petrification device for himself. If Senkuu plays his cards right, he could gain a powerful ally and win the war once and for all.

A high school loner is given the part-time job of a lifetime as a modern day ninja tasked to perform international assassinations. After World War II, Allied Command in Japan developed a new agency to help manage terrorism and violence within the Pacific region. The agency was staffed with ninja and they were initially tasked to handle domestic affairs. Eventually that program grew to its current form, managing 20,000 ninja across a range of domestic and international affairs. One of those ninjas happens to be Kudo. The seventeen-year-old high school loser is now poised to be the next line of defense against a potential surge in foreign assassins invading Tokyo.

Mardock and his friend Chewy traverse the universe and solve problems from planet to planet.