Nemu notes that rumors will die with her, so she and Touka plan to make a backup on server.
They chose Ai as test subject after getting her agreement.
The duo informed the Mikazuki Manor of their plans, and Sana decides to stand guard for them just in case.
Ai wants to see Sana, and the feeling is mutual, this caused the experiment to fail, and Sana defending Nemu in her PM form caused some unwanted trouble.
A new rumor is born from Ai and Sana's desire to see each other, using Sana and Nemu's mana to gain sentience.
But it is not strong enough to have an actual form, so it is hard to deal with her since she is causing trouble by dragging in people who wants to see her and into a nightmare.
While she is too weak to create her own field, it makes it hard to defeat her.
Sana thinks she is to be blamed for the birth of the new rumor, so she tried to lure it out.
But the lack of form makes Sana become a victim to nightmares.
Luckily, her new family gave her courage to face her demons.
She tried luring out the rumor again, this time with her new family, Nemu and Touka's help.
They discovered too late that the rumor is NOT looking for Sana.
While she is born from Ai and Sana's desire to see each other, the rumor has no idea who she is, and who she is looking for, so she went amok and stole some of Nemu's life force as they tried to deal with her, finally gaining a physical form.
The rumor then kidnapped Ui and Sakurako's consciousness into her barrier and escaped.
Part 2
The team deducted that the rumor is mainly made from Sana and Ai's desire to see each other, so they need a fusion form of the two to defeat the rumor.
Touka suggests fusion, but Tsuruno rejected it for Sana since it is way too dangerous. Besides, there is no extra mana to power the fusion.
Nemu noted that the Chocolate Madame rumor has her stash of emotional energy collected from the previous Valentine must still be around somewhere. While she can no longer collect energy by taking away its victims possibilities, and that all have been returned after Iroha and Yachiyo finish it off, the stash which is just energy is still around and can be use.
But they need to get Sakurako out first, since only she knows where it is.
Sana gets caught in a vicious cycle where she is blaming herself for causing the troubles and still needs to ask Ai for help, so she bolt in shame, guilt and disappointment at herself.
Iroha found her by following a pair of cute cats. After a pep talk on how Sana has grown much emotionally since they met, Sana grew some spine and decide to face Ai again.
The plan is simple, someone lures the rumor out and take Ui's place. Sakurako can find her way out easily on her own. Sana is the best choice since they one left inside need to beat the rumor to get free.
The others will find the stash once Sakurako is free.
Nemu plans to rewrite Ai-chan so Sana can fuse with her.
The rescue is successful since Sana, gaining new confidence from her family can take on the scathing comments from the goro-goro-nekos in the rumor’s barrier. She is able to calm the rumor down after agreeing to stay in return of freeing Ui. Sakurako got out on her own.
With Sakurako as their guide, team Mikazuki collected all the stash of energy left over by Chocolate Madame. These contains the emotions of all the girls featured in this year's Valentine costume story, so it seems the Madame stole from them before getting defeated by Yachiyo and Iroha.
Using their abilities, Ui collects the energy, passing it to Touka who turns it into mana, before passing it to Nemu who now can edit Ai's rumor content.
The process is a success, allowing Sana and Ai to fuse after they have a short by warm heart to heart. Ai also got rid of Alina's pollution and took on an anime-like form.
The rumor is happy and excited to finally find who she is looking for: Sana and Ai in one body and manifest.
She disappears peacefully after Sana and Ai euthanized her.
Taking whatever remaining time they have until the mana used to maintain the fusion burns out, Sana brings Ai to her real home, the Mikazuki manor, and share her new and happy life with Ai.
They exchange vows, Sana promising to grow strong as the shield of her new family, while Ai will watch over Sana as she grows strong. Even if they are apart, their thoughts are with each other.
Sana returned back to reality alone but content. Nemu decides the risks are too high, so the experiment will end. She will find other ways to ensure the rumors can live on even if she dies.
Everyone is happy Sana is back, especially Touka since she got a precious data from the whole fuss.
Ai shares her experience with her rumor comrades in the book, and she finds a kindred spirit in Sakurako.
Sana grows as a person after a true farewell with Ai.
