After experimenting with several types of fortune-telling, Momoka learns that her romantic destiny with Fuyuki will be realised in an onsen. Thus she engineers a scheme of her own, allowing Fuyuki to 'win' an onsen trip for the whole Hinata family and one guest... problems arise when Keroro and Koyuki have their minds set on that guest ticket at the same time. While Keroro is easily dispatched with the task of solving a Rubik's Cube, Kururu forces Momoka and Koyuki to battle each other for the guest ticket, and tradition clashes with technology as Koyuki pits her ninja skills against Momoka's new robotic battlesuit!
Fuyuki is late for school, while Keroro is fleeing Natsumi's wrath after breaking her mug - the two meet each other on a shortcut to school. With Mutsumi standing in for the narrator, the simple act of walking down this seldom-used lane, filled with old memories and new discoveries, turns into an evening to remember.
