The Planet Group is formed of powerful families that represent each planet in our solar system and the central Sun Family. Midori is the eldest son of the Earth Family, who is just now entering his high school life in the Planetary Academy. Other than his family name, however, Midori has little going for him. He doesn't get good grades and is shy and socially awkward.

His low self-esteem isn't helped by the general disdain his father and younger brother openly show towards him. All they want is for him to not further "dirty" the family name, by staying silent and not standing out in public. But at his new high school, Midori is surprised by the kindness of the other Planet children, particularly Yuudai Jupiter, who takes Midori under his wing on the first day. Will attending the Planetary Academy mark the beginning of a change in Midori's life, or is there no hope for him after all?