Kusakabe Renji, a young man working at a game centre, sees an English girl named Lily Baker playing a crane game on Valentine's Day. Seeing her fail repeatedly to win a prize, Renji can't help but take action. The day after Lily finally gets her plushie, Renji receives an unexpected message from her that reads, "Be my valentine!" What started as a misunderstanding leads to cultural exchange!

One day, Miu Takigawa suddenly receives a letter notifying her that she has been chosen as a member of a brand-new project. Half in disbelief, she heads over to the location stated on the letter. There, she finds seven other girls summoned there in the same fashion. The girls behold a giant, top-secret facility. They stand in bewilderment as they are told: "You are going to debut for a major record label as an idol group." A new kind of idol, never-before-seen, is about to be born here...

A strange old woman allows a teenage runaway and a young orphan to stay in an abandoned house that overlooks the sea. However, when a menacing entity threatens their new home, they must band together and face their fears to save it.