By Nankin Gureko.

Yuji Midorikawa is a high school student whose secret identity is "Green" in the school battalion unit, Gakusei 5 (G5). G5 is a special unit trained to fight and protect Earth against the invasion of Galactic force Gurdark and composed of five members (Red, Green, Blue, Yellow, and Pink). After an intense battle with Gurdark, the queen named Mayura is injured and goes into hiding on Earth.

When Yuji finds Mayura and her pet, Poyo, hungry in a park, he decides to take them in. Mayura then tells Yuji that she is tired of the Gurdark life style and wants to look for a boyfriend, but Yuji is worried that other members will find out that he is living with the archenemy…