As tensions rise between the denizens of Planet Develuke, particularly the royal women, and the Earthlings, notably the hapless Rito Yuki, chaos ensues. With junior princesses Nana and Momo enrolling in an Earth school under the supervision of their elder sister LaLa, one would expect a smooth transition. However, when Momo decides to spice up Rito's bond with LaLa by introducing some sisterly affection, LaLa is quick to intervene and protect her domain from potential harem drama. The situation takes a drastic turn with the arrival of Yami, the formidable Golden Darkness, accompanied by a group of possessed high school students. This unexpected development threatens to make Rito's existence more tumultuous than ever. Unless, of course, a certain partially demonic princess unleashes her Develukean prowess to restore order among these celestial beings!