The spaceship AAB-Gamma is dispatched from FAFC headquarters in Japan to make a landing on the planet Mars and investigate reports of UFOs in the area. As they near the red planet, they encounter a mysterious UFO that coats the ship's hull with unusual spores. Taking one of the specimens back to earth, it soon develops and grows into a giant chicken-lizard-alien monster that tramples Japan.
Set during the last days of the Tokugawa (Edo) Period, Moeyo-ken tells the story of Hijikata Toshizo and the Shinsengumi. Hijikata Toshizo is a samurai eager to test his skills and sword and make his first kill. The dojo he belongs to practices the Tennen Rishin style and teaches this to farmers. Not considered real samurai by other dojo's, they receive a request for a duel by a rival dojo practicing the Kogen Itto style. Sohaku Rokusha, a teacher there, challenges them and fights with Hijikata Toshizo. The outcome of the fight creates a deadly animosity between them that lasts through the ages.
Suzuko, a woman in her twenties who has a brother with political problems (due to communist reprisals), lives for over five years in a love affair with Tate who's a young lieutenant in the Army, ultimately becoming a right-wing fundamentalist revolutionary. She marries another man, one totally dedicated to the rigorous practices of Noh theatre, in an arranged marriage, but the bond that connects her with Tate is too strong.
