Kotaro Lives Alone

Fuutarou Uesugi is a poor, antisocial ace student who one day meets the rich transfer student Itsuki Nakano. They argue but when Uesugi realizes he is to be her tutor, he tries to get on better terms. While trying to do so he meets four other girls.

The story is set in the galaxy located near the center of the universe. There are Planet Aernia (a planet for Heroes) and Planet Orbs (a planet for robots), governed by Orbiton, in this same galaxy. Various countries are present in Planet Aernia; they are, Volculm (volcanic country of fire), Zylan (oceanic country of water), Elvan (green-rich country of forest), and Aleum (celestial country of clouds). Antania, is a nucleus of all the present countries. It has an academy that fosters Heroes. Under the reign of the Governor General, Antania upholds a national policy to train Heroes to prevent Planet Aernia to be infringed by the Dark Desire. Heroes are not only the reliable source of battle who have special abilities to freely use the battle discs, but also a symbol of unfailing justice.