While alien invaders called Kiseichuu plot to eradicate humanity, Retto Enjō discovers that his childhood friend Kirara has withdrawn due to a traumatic experience and worries.

Retto Enjō joins the HxEros team to fight the Kiseichuu, an alien race that feeds on human libido known as H-energy.

After joining the team as Hxe Yellow, Kirara is unable to release her full potential because she is lacking H-energy; Momoka Momozono, also known as Hxe Pink, is irritated and scolds Kirara.

Maihime Shirayuk has hidden eros but lacks confidence; Sora Tenkuji, aka Hxe Blue, has a secret hobby and Kirara finds out Sora's secret.

When Kirara is abducted during battle, Retto and the others head to a nest of Kiseichuus to rescue her; Kirara frees herself from her restraints and encounters Chacha, a princess of Kiseichuus who is imprisoned because of her mutation.

Chacha joins as a new member and begins living with the team in the same dormitory; Chacha enters Retto's consciousness to discover the source of his H-energy.