Himari has a strange dream in which she meets a man named Sanetoshi, who shows her various books containing her memories. In elementary school, she formed a group called Triple-H with her best friends, Hibari and Hikari. When she argued with her mother over buying a wrong ribbon, her mother became scarred from a falling mirror, she and her friends tried to kill a koi for its blood to heal her mother. She left elementary school due to her illness whilst her friends went on to become idols. Upon waking up after vaguely recollecting a soulmate she once had, Himari hears from Ringo about Shoma's accident.

Shoma wakes up in hospital with supposedly minor injuries, keeping quiet about what happened between him and Ringo from his siblings. As Ringo explains what happened to her diary to him, Natsume disguises herself as a nurse and kidnaps Shoma, demanding the other half of the diary from Kanba and Ringo in exchange for his life. Deciding the to leave the diary half with Ringo, Kanba goes to find Shoma, whilst Ringo is told to surrender the diary herself. After luring Kanba into a trap and kissing him, Natsume escapes but is confronted by another person in a penguin hat, whom Natsume identifies as Mario.

Kanba goes to confront Natsume about the memory-erasing balls and why she desires the diary, unaware that she only has half of it. Meanwhile, Ringo is still determined to complete Project M with or without the diary, making a love potion to give to Tabuki, which actually seems to work. As Ringo decides she can't go through with it, Yuri helps her come to the realisation that she is actually in love with Shoma. As Penguin Himari brings Shoma and Ringo into a Survival Strategy meeting, Himari tells them about the day 16 years ago when Momoka died and she was born, which turns out to be the day that Shoma and Kanba were also born.

After realizing that she was tricked by Yuri, Masako reminisces about her grandfather, a powerful business tycoon who expelled her father claiming that he was not strong enough to be allowed a place in the Natsume family. After dreaming countless times about having him killed, Masako rejoiced when her grandfather inadvertedly poisoned himself to death by eating ill prepared Fugu. Masako since then assumed control of her family's corporation but was sad that her father had never returned home, until somehow her grandfather's spirit posessed Mario's body and forced her to eat the same poison that killed him to protect her brother, but Sanetoshi appears to save her life. Later, Masako sees Kanba hanging out with the same elusive men who took her father away and Sanetoshi asks Masako to join them in his plan to "put the world back on track" but she promptly refuses.

Shouma tries to dissuade Kanba with no success while Ringo also boards the train, claiming she had learned from the present she got from Himari's friends the secret spell contained into the now lost diary. She activates the spell determined to sacrifice herself to save Himari and the others, but Shouma takes the burden to himself instead while Kanba sacrifices himself to ressurect Himari for good. The terrorist attack is stopped and both Himari and Ringo are found unconsious with no memories about the brothers or everything that happened. The same occurs for Masako whose brother Mario also fully recovers. While hanging with Ringo at her house, Himari finds a message left by Kanba and Shouma and starts crying without knowing the reason why while Shouma and Kanba, in children form, pass in front of her house accompanied by the four penguins.