The chapter begins with Raku collapsing down on the ground due to an appendicitis. The chapter picks up later with Raku recovering in hospital, after having his appendix surgically removed. Chitoge comes to visit and leaves once she knows Raku is ok as well as receiving a PSA about going to doctor if you have persistent stomach pains. She also texts everyone that they can visit Raku in the hospital. Raku's first visitor is Shu, who comes with some apples, but he is more interested in hot nurses than his friend's wellbeing. Kosaki is the next to visit and she too brings some apples and offers to peel them for Raku. There is some awkward tension as Kosaki is waiting on Ruri to come visit, but she has bailed on her, so Kosaki bails on Raku. Seishiro visits to pay her respects to her mistress's boyfriend (it is not like she cares, idiot!) and leaves after peeling him an apple. Marika rushes over to visit and as well as to peel an apple and she tries to camp out in his hospital room, which she tried to do earlier on hospital grounds but was rightly thrown out for trespassing. Raku gets a few more visitors, before realising that night he needs to thank Chitoge for letting everyone know that he could have visitors, when she appears outside his window to give him an apple. Unfortunately, Raku has eaten all he apples that were gifted to him and that has given him stomach pains and his hospital stay is extended by 2 days.

In discussion with Raku about his pendant, Chitoge asks if she could read the picture book which inspired it again, with the only known copy being Kosaki's which is in Raku's possession, so they head to his house to read it. When they arrive, everyone in Shuei-Gumi is dressed up smartly as the group are playing host to the boss of the Char Siu Kai Chinese Mafia Syndicate, which is one of the biggest organisations in the world. Also visiting is Yui Kanakura, who is an older childhood friend of Raku that knows of the Beehive gang and their leader, as evidenced by her recognising Chitoge's surname. Raku's father approaches he reunion to introduce the Char Siu Kai boss to Raku, as Yui Kanakura and had not told Raku anything because Yui had requested it. Yui, Raku and Chitoge all sit down, so Yui can reminisce about her time living with Raku, who hasn't seen her since Year 2 (US 2nd grade), 6 or 7 years ago.
Now, if you were wondering, Raku is in his 2nd year of Japanese High School and thus is in the equivalent of Year 12 (US 12th grade), so 6/7 years would put him in Year 5 (US 5th grade), also Year 2 (US 2nd grade) is about 10 years ago, year after Raku got his pendant (remember it was 10 years ago at the start of the series, so it now 11 years ago) - so one of these statements is wrong.
Raku and Yui appear to get on like siblings, but Chitoge is not fully convinced, with the fact that Raku is Yui's first kiss not helping matters. At the end of the conversation, Yui reveals that she will be joining them at Bonyari High School, which is the revealed the next day to be as their home-room teacher.

Raku expresses his surprise at the revelation from the end of the last chapter, while his tone of familiarity with Yui surprises his fellow classmates. Yui explains that she was so incredibly smart, so skipped few years of education to become a qualified teacher by age 19. Shu then introduces himself to Yui, who fondly remembers him and gets him to behave like a dog front of the class. She then approaches Marika, who tries to deny that Yui knows her, but the conversation is interrupted when a student asks where Yui is staying, so she reveals that it will be with Raku - uproar from the male members of the class ensues.
Back at the Shuei-Gumi household, Raku's father ignores his son's protestations at Yui's living arrangements and is tasked to help clear out the spare room next to his so that is habitable for Yui. As they're tidying up Raku asks why Yui wanted to go to school with him, with the answer given is to work it out himself and that while he may have grown physically, mentally he is still a child. Once they finished tidying, Yui begins to strip before Raku can leave and fails to see the problem when Raku chastises her for it so much that she offers to bathe with him; Raku storms off embarrassed. That night someone disturbs Raku's sleep by entering his room and the someone is Yui who has sleep-walked into his futon. As Raku plans to resolve this issue (he can't sleep in the same bed as an unmarried woman that just wouldn't do), he notices an old-looking key around Yui neck: could she be another one of his pendant girls?

Raku waits by his window, away from his futon, until Yui wakes up the next morning to ask her if she ever went on a trip with him about 10 years ago and made promise with her using her and his pendant. Her response is to just wait, but reveals she does know something.
After her class, Yui summons Raku, Chitoge, Kosaki, Marika and Seishiro to the school roof and explains that she has a key and was on that trip 10 years ago. However, she doesn't remember anything about a promise, but she does remember how well Chitoge and Kosaki got on as well as how well she and Marika got on, although Marika doesn't seem to remember. To jog her memory, she reveals that one time everyone bathed together and Marika overheated and fainted, so only her butt was visible. This still doesn't trigger any memories for Marika, so Yui mentions about a love letter which Marika does remember, along with how much Yui annoyed her. Chitoge reminds Yui not to pull any funny business whilst staying at Raku's, which reminds Yui how comfy Raku's futon was and that triggers rage in Seishiro, Chitoge, and Marika and despair in Kosaki.
Back home, Yui remarks how popular Raku is, which is music to his ears. He then asks what she meant by her answer to the question he asked when she woke up and her response is that he doesn't remember a promise that the 2 made. When pressed for more information, Yui responds with a question, asking when Raku finds out who he made the promise with 10 years ago, is he still going to confess his feelings to that person.

Raku is perplexed by the question Yui posed to him at the end of the last chapter, so she reminds him that he has someone important to him right now and she will reveal all when he makes decision between the 2 - assuming that they are 2 different people. She heads to her room and tells him that his pendant won't open right now, but refuses to elaborate any further.
Raku gets little to no sleep that night as he is still agonising over what she said as well as Yui sleep-walking into his futon. At school, Yui comes over to get her lunch from Raku, before noticing he has bed hair and attempts to fix it, only for Marika to interject saying, that it is wrong for a teacher to act this way towards a student. Yui agrees with her, so switches from 'teacher mode' to 'big sister mode' by taking her glasses off and fixes Raku's bed hair. Back at home he spots Night (Yui's bodyguard), who warns him not to underestimate Yui (also not to harm her, as she would finish him off in 3 seconds), as she managed to transform the Char Siu from a disorganised mess to a strong cohesive unit in 2 years, also she has never ever sleep-walked. Raku also spots his father and asks him if he knows why Yui wanted to go to his school and his father reveals that Raku is only family she has left as everyone related to her is dead or didn't exist. That night, after Yui sleepwalks into his futon, Raku remembers when he protected Yui from children in Year 6 (US 6th grade), who were bullying her, and the promise he made to protect which renews to himself, as he is her brother. The next morning Yui wakes up and notices that Raku is still asleep, so she confesses her romantic love for him - add another to the harem!

The most annoying thing about Yui is that she is in love with Raku and is also a member of the inner circle of the harem - the key holders. This is because her inclusion just adds an extra complication into the series, in which there is now 6 members to this harem, and as Raku doesn't see her as a possible romantic partner meaning any Yui-focussed chapters have no romantic weight to them, because Raku has already made up his mind about her: she is his sister. Marika is similar in this regard, as her brazen attitude conflicts against Raku's more reserved nature, making anything she does a turn off for him, although this is more action than lore, which is more excusable. In other words: I dislike Yui because her dynamic with Raku is that she is in love him, whereas I dislike Marika because what she does because she is in love with Raku.
To be honest I think Yui would have better served as someone who plays a similar role that Ruri plays with regards to her dynamic with Kosaki: a wing-woman trying to get her friend with the guy she likes. I believe that Marika would be an ideal candidate for Yui to be a wing-woman for, as while Marika needs no assistance in trying to get with Raku, the past they share makes perfect sense for a dynamic like this between them to exist.

The chapter's narrator is Ninjiro Fukuda, who is the assistant home-room teacher for the gang's class. Today, he is, along with Yui, discussing with each student their future plans. They have got as far as Ruri, who knows what she needs to do in the future to achieve a successful career as a translator, but she is the last of good ones as the ones left are either problems themselves or their families are. Up first is Marika, who future plans are to marry Raku and there is no way that isn't happening, even if her grades are poor and Raku might not want to marry her. Next is Seishiro, whose future is dependent on what Chitoge does, which will probably mean joining Shuei-Gumi if Chitoge marries Raku - much to Claude's anger and Seishiro's embarrassment. Kosaki doesn't know what she wants to do, but her mother does and decides that her daughter will work at the family's shop along with Raku to make the business grow. Chitoge also doesn't know what to do, but her grades and family connections means she could easily work for Flower Co, which is headed up by her mother, or marry Raku and join his family instead. The final interviewee is Raku, who like Ruri, knows what career he wants and universities/colleges he aims to enrol in to help achieve that and if all else fails, he can take over Shuei-Gumi yakuza crime syndicate and marry Yui. The chapter ends with all 6 children and their parental represent meeting in the corridor and the expected carnage ensues.

Following her discussion with her teachers, Kosaki has been thinking what she wants to do in her future and decides to ask Ruri for advice. While Kosaki isn't opposed to taking over the family business, she wonders if there is something else for her to do, but Ruri doesn't know. Kosaki asks why Ruri wants to be translator so Ruri explains that she decided after feeling her own translation of a book she was reading was million times better than what the official translator did. The next day, Kosaki asks Seishiro for advice and receives a detailed analysis with charts and graphs and everything, which ultimately concludes that a job in the service industry that requires a creative touch is best: an example would be a running a Japanese sweets shop. Not wanting her future to be already determined, Kosaki seeks out more advice from a kindred spirit in Chitoge, whose only advice comes from her mother, Hana, that everyone owes the world to put their talents at work, so aim for what you're good at. After school, she rests at her secret spot from chapter 27 when Raku passes by. Kosaki asks Raku about why he wants to be a civil servant and his answer is that it is a solid upstanding career that keeps him away from a life of crime - I guess he hasn't got the maths skills to be a police accountant. Raku reminds her that right now, it is still alright not to know what you want to do in your future and she should take as long it should take to find out what she wants to do. Kosaki asks if she would make a great wife and clarifies that her future husband is hypothetical stranger and not anyone specific that she knows, so Raku's response is for her to marry someone who can cook (like Raku Ichijo for example). This conversation inspires Kosaki to stop worrying and to make dinner for her family that night - they all flee at the declaration.

Seishiro and Paula have been tasked to infiltrate a party on a cruise ship being hosted by Seccachino (an enemy of Beehive) and steal a disc from that contains top-secret information. However, just before they are about to board, Paula calls in sick after eating 40 ice creams of which some of them may have been poisoned, so Seishiro can't attend the party as it only for boy-girl pairs (remember Claude still thinks that Seishiro is a boy), but conveniently Raku is in the harbour after a fruitless day fishing and is immediately roped in. Raku and Seishiro infiltrate the party with Seishiro in Paula's outfit and Raku in hers, but as neither outfit really fits each other, they head to a boutique to change into different clothes (I don't know how they paid for it; I assume Claude gave Seishiro a credit card with near limitless funds to cover costs needed to maintain their cover on the boat). After Raku bashfully and vaguely compliments Seishiro's new outfit, he recommends that she talks more like Marika (which she initially takes to mean with a US south/Kyushu accent) to seem more feminine and to smile more, which she fails at. They spot Seccachino and Seishiro begins to walk over to begin talking to him, but is mobbed by other guests and needs Raku to back her up and so lose sight of Seccachino, but spot him going into the casino, where he has all of the bunny girls surround him.

Seccachino is approached by a bunny girl (Seishiro) with an offer of a Vodka Martini and a massage, which he graciously accepts both. The massage allows Seishiro to identify where the disc is, but Seccachino leaves before she can swipe it, so Raku and Seishiro chase him down to the pool. There Seccachino has surrounded himself with women wearing dark blue one-piece swimsuits (typical Japanese school swimsuits) and Seishiro is 'disheartened' that she won't be able to get close, as such swimsuits aren't available on the ship; Raku comes over with a dark blue one-piece swimsuit he bought from a shop on the ship. By the time she has changed, Seccachino has left the pool. Frustrated that she is spending more time changing into costumes than getting close to Seccachino, she dresses as a waiter and is immediately rumbled by him, along with Raku being found in his hiding spot amongst some bushes. Realising that the famed Black Tiger is a girl, Seccachino demands that she strip in an exchange for their lives and Seishiro begins to comply, only for Raku to stop her and criticise Seccachino for the disgusting way he treats women. Before either can die, the whole ship shakes, thanks to the rocket launched by Paula from her own boat, which distracts everyone enough that Seishiro can beat up both Seccachino and his guards and take the disc. Seishiro leads Raku through a window, which rips her clothes, to escape and whilst in the water, she asks why he defended her (a guy doesn't need a reason to defend a woman) as well as thanking him with a smile. Paula passes by on her boat, before deciding to leave to give the 'lovebirds' some alone time.
The bonus comic is Night describing to Raku how Yui managed to unite Char Siu, using methods she doesn't understand, but Raku does.
The Magical girls bonus comic continues with the mastermind behind all the evil-doing being revealed to be the nefarious Dr Maiko, who is just like his normal series counterpart in one way.