What would you do if you suddenly found yourself in the middle of a war? Teenager Amuro Ray sees his life shattered when war comes to his home. During the chaos, Amuro finds himself inside the mobile suit Gundam, the Earth Federation's new secret weapon, and he somehow gets it to work. Amuro and the other refugees flee their homeland on the warship White Base. This group of children and inexperienced soldiers will change the outcome of the war.

The Yomota family is small and typical: father Kinekuni (42), mother Tamiko (38), and son Inumaru (17). One day, a beautiful girl appears at their front door, calling herself "Maroko Yomota," granddaughter of Inumaru who travels back in time with a time machine to visit her ancestors. Despite of Tamiko's strong objection, Kinekuni and Inumaru welcome her to stay with them, and the structure of a happy family has begun to collapse.