Yui Kanakura

is a childhood friend of Raku Ichijō as well as his current homeroom teacher. Yui is also the head of the Chinese mafia group, Char Siu (Chinese: 叉燒, Chāshāo). Yui is also in possession of a fourth key but has confirmed to Raku that she is not the girl he had made a promise with ten years prior.

Appearance
Yui has long, silky dark hair with a pinkish-violet tinge (similar to her eye colour in some occasions) and is personalised by several braids while wearing a flowered crown, earrings and a key necklace. In her teacher attire, Yui wears a proper teacher's uniform, glasses and ties her hair into a bun while still leaving her flowered hair crown and allowing her braids to fall. Her eyes are occasionally blue-green, but sometimes pinkish-violet.

As a child, Yui sports much shorter hair.

Personality
Yui is generally described as very optimistic and an easygoing teenage girl. Despite having inherited the title of a don of a large Chinese mafia group, Yui simultaneously works as a homeroom teacher. It can hence be implied that she has a great sense of responsibility and industriousness. This is further magnified as stated by Ie - Yui's personal aide - that Yui had united all the scrambled members of her faction in a mere two years during her jurisdiction and had maintained the stability within the Char Siu, also implying that Yui is fearsome and a very powerful figure.

In actuality, as revealed in Chapter 133.1, Yui united her faction by asking the men not to fight as she could not stand seeing any of them hurt with a teared-stained face. This shows that Yui can be very childish as well and does not condone violence. While in the line of work - as a teacher for example - Yui is focused and displays a certain level of skillfulness, in contrast to her laid-back character as shown during the stay at Raku's estate. Overall, Yui is a kind and mature person in heart who values friendship with the people she once met despite her tendency to tease them, with Raku and Marika in particular and being quite secretive in some certain aspects.

Relationships
"Main Article: Relationships of Yui Kanakura"

Background
During her childhood, Yui was friends with Raku Ichijō and the two frequently bonded and played with one another. Yui was attracted by Raku's enthusiastic and overly caring personality whereas Raku began looking up to Yui as an older sister. Meanwhile, Yui was also acquainted with Chitoge Kirisaki, Kosaki Onodera, Seishirō Tsugumi, Marika Tachibana - the latter whom she seems to know well - and Shū Maiko during her stay. Afterwards, Yui bid farewell to Raku and departed overseas where, in the years to come, she eventually inherited the title as the don of the Char Siu mafia group and managed to unite it. During her reign as don, Yui lost both of her parents, leaving her with no relatives she can trust. As a result, Yui decided to return to Japan and reunite with what she considers her only remaining family member - Raku - and to become his teacher.

Second Year Arc
Yui returns to Japan in nostalgia and makes a surprise visit at Raku's estate where she later meets Raku himself - much to her excitement - and his girlfriend, Chitoge, whom of which Yui recognizes the daughter of the head of the Beehive faction. After expressing her joy of returning to the home she once lived in, Yui reveals herself as the head of a famed Chinese mafia group - Char Siu - much to Raku and Chitoge's surprise. Afterwards, while reminiscing their childhood memories, Yui mentions of Raku stealing her first kiss, much to the shock of Raku and Chitoge. Further surprising them, Yui states her intentions of transferring to Raku's school, which is revealed to be their new homeroom teacher days later. As the class begins to warm up with their new homeroom adviser, Raku's bewilderment and casual addressing to Yui causes a slight uproar towards the majority of jealous boys in the classroom questioning Raku and his involvement with their new teacher. Yui explains how she skipped several grade levels and having acquired a teaching license that made her an approved teacher. By then, Yui meets several faces such as Shū and Marika and Kosaki. When asked by the class on where she currently lives, Yui openly reveals that she will be living at Raku's estate during her limited stay in Japan, spurring yet again another uproar from the jealous males towards Raku.

Back in Raku's estate, Raku questions his father of freely allowing Yui to stay together with him under the same roof whereas his father explains that it was Yui's wish that granted her to stay alongside them. Afterwards, while organizing her belongings in her room with the help of Raku, the latter asks Yui why she wanted to become teacher, whereas Yui explained that she actually wanted to be in the same school as Raku albeit as another senior student but wasn't resolved and instead, made her way to become a teacher. When asked by Raku why she wanted to be in the same school as him, Yui glances at Raku, vaguely remarking his growth yet teasing him for still being immature on the inside, much to Raku's bewilderment. Afterwards, while intending to take a bath after thanking Raku for his help in organizing her belongings, Yui attempted to strip in front of Raku, causing him to drop the box he was holding and scolds Yui for her somewhat obscene act. While Yui explains herself as a habit she had done during their childhood, Yui teases Raku into taking a bath together for old time's sake, causing Raku to walk out in embarrassment, much to Yui's amusement. That same night, Yui unwittingly sleep walks into Raku's room and lays down, whereas Raku discovers a key from her that may allude to the promise girl he made a vow with a decade ago.

Once waking up, Yui realizes she fell asleep in Raku's bedroom and found the latter by a corner with bags under his eyes. Shocked, Yui asks Raku if he had done something to her in her sleep, causing Raku to retort. Sleep-deprived, he states how hectic the day before was and immediately asks Yui about her knowledge regarding a promise he made while on a trip ten years ago. While Yui remarks how Raku had still kept the locket in his possession and implying that the other girls have kept their keys also, Yui asks Raku to wait for the answer to his question.

During her class, Yui, while lecturing, left a reminder to students namely Raku, Chitoge, Kosaki, Marika and Seishirō to meet with her once their class had ended. After their dismissal, Yui presents her key to the called students, publicizing her involvement to Raku's unknown promise while stating her shock how she met all her childhood acquaintances in one class. Afterwards, Yui reveals her past relationships with each and everyone and the nostalgia of meeting them again, whom of which had no memory of their time with Yui in childhood with the exception of Marika, who still had past memories with Yui. When asked by Kosaki if she still remembers the promise Raku made, Yui came out with nothing, much to their shock. Despite having no memories of Raku's promise, Yui enlightens the girls with her memories of them during their childhood, with Chitoge and Kosaki being the closest to one another and Marika, due to being physically frail, instead spent most of her time with Yui. Whereas Marika tried to deny most of Yui's claims about her, Yui shocks everyone by telling them how they took a bath together as a group. After teasing Marika by chanting the latter's love poem to Raku, Marika gives in and reveals that she still remembers Yui to the present while continuing to despise her. As the girls question Raku if she had done anything to Yui while staying at his house, Yui gleefully states how she had a good night's rest at Raku's bed place and plans to sleep there again, causing a spur from the girls and Raku.

At Raku's house, as Yui felt amused of all the happenings, apologized to Raku for not being of use with telling him of his forgotten promise. Afterwards, in surprise, Yui asks Raku about the promise he made with her and discloses to Raku further hints of the true identity of the girl he made a promise with, much to Raku's bewilderment. Denying to give an answer, Yui instead questions Raku if he is really willing to fall in love with the promised girl by the time he identifies her. Knowing that Raku plans to know the identity of the girl he made a promise with was only out of curiosity and given the issue that the present is different from the past, Yui tells Raku that she will plan to reveal all that she knows regarding his promise by the time he makes up his mind of choosing the person he considers the most important. Feeling apologetic, Yui gives Raku a disclosure that his pendant won't unlock in its current state, much to Raku's bewilderment.

The following day, Yui gets scolded again by Raku for intruding in his sleeping quarters, yet Yui teases him of sleeping along with her whilst Raku slept on the floor. Later at her classroom, Yui gets greeted by her students per usual and acts clingy towards Raku until Marika intervenes by stating the inappropriateness of intimacy between a teacher and student. As a result, Yui takes off her glasses - claiming to have revoked her teacher persona - and proceeds to pamper Raku, much to Marika's distress. By the end of the day, while walking side-by-side with Raku, Yui asks Raku to wait for her while she changes and then they proceed to shop together. That evening, Yui barges to Raku's room to sleep per usual.

By morning, Yui finds herself yet again at Raku's room and whispers to the sleeping Raku that she had always liked him more than just a younger brother.

On one particular day, Yui, alongside Ninjirou - the sub-homeroom teacher of the class Yui is assigned - work together during her students' career counselling. During the counseling, Yui compliments Ruri for her well-grounded career, gets warned by Marika's father of an arrest if ever she does anything unusual, teases Marika for visiting her and Raku daily if ever they wed, greets Claude who is aware of Yui's position as the don of the Char Siu, and gives Raku an option of acting as his bride whenever he fails to pursue his career.

Back in the Ichijou household, Yui gets scolded again by Raku for her sleeping habits as he gets notified by his father's men of Chitoge's arrival. Knowing that Raku and Chitoge are planning to go on a date, Yui forces Raku to allow herself to accompany the two. After sending Raku to buy them beverages, Yui states her intentions to talk with Chitoge alone. As Chitoge chats with Yui in regards to the background of her relationship with Raku, Yui's confirms her suspicions of the pair faking their relationship. After Chitoge explains to Yui the consequences behind their relationship, Yui asks Chitoge if she still has feelings for Raku after ten years, which Chitoge greatly dismisses out of embarrassment. Afterwards, Yui reveals to Chitoge that she loves Raku but not as a younger brother and declares herself as a rival of Chitoge for Raku's feelings.

The following day, just as Raku wakes up and wonders about the whereabouts of his father's men, Yui informs Raku that the group went on a vacation followed by Yui applauding Raku for being studious. After teasing Raku of engaging in any activity they want considering that they are alone together in the mansion, Yui gets amused by the surprise visit of Chitoge, Kosaki, Marika, Seishirou, Ruri and Shuu. Not wanting to act rude, Yui prompts Raku to entertain his guests as she cooks them their meals which consist of gyoza-oriented dishes. After eating Yui's meals, the group proceeds to play the King Game. During Yui's turn as king, she commands numbers 2 and 7 to name the person whom they like which reveals to be Shuu and Marika. After fulfilling their respective orders, Raku receives more guests consisting of Haru, Fuu and Paula, much to Yui's amusement. After many rounds, Yui reminds her guests of the time and wonders if they are intending of heading home followed by the group exclaiming that they are going to stay the night. Later that evening, with the others asleep, Yui holds a conversation with Raku about how she had fun during her stay as she wasn't able to mingle with anyone of her age after being separated with Raku a decade ago, adding that she was happy since nobody of her childhood friends changed, thanking Raku as a result. As Yui prompts Raku to take a bath together for the sake of nostalgia, Marika overhears and scowls at Yui, waking everybody and process while declaring that they will continue to play throughout the night.

After Chitoge accidentally makes Yui's cake fall apart during Yui's 20th birthday ceremony, she and Yui have a bath together to wash off. As Chitoge apologizes to Yui for ruining her birthday ceremony, Yui actually thanks her for getting her out of the stiff reunion with everyone at the party. Yui then also thanks Chitoge for coming to her party because she was afraid she wasn't going to come due to declaring war for Raku's love the last time they were alone. Chitoge asks Yui why she isn't getting a head start to claim Raku if she likes him. Yui smiles and tells her that she likes her just as much as she does to Raku. Although her feelings toward Raku are legitimate, she loves her, Marika, Tsugumi, and Kosaki just as much because of the irreplaceable bond she had with them ten years ago and in the present. She tells Chitoge that if she had a head start to get Raku it wouldn't be fair and that she would still be happy if Chitoge or Marika end up with Raku instead. As Yui drys off from her bath, Ie comes up to her and tells her that she has a marriage proposal she can't refuse. Ie gives Yui the chance to try and convince Raku to marry her within a week, but if she can't do that, she will have to get married. Marika was able to hear their conversation as she hid behind a wall in the hallway.

The next day, Yui becomes nervous and jittery as she teaches the class. Yui worries about the marriage and Chitoge and Marika's reaction to her trying to make Raku hers. After school, Marika comes visits Yui in the classroom and congratulates her on her engagement. Yui bones on about how her fiancé was a good person and how it's her job as the don to get married. Marika then becomes mad at her for not changing since ten years ago and how she always hides her feelings because she's afraid she or someone else could get hurt.

Feeling confident, Yui confesses to Raku but eventually got rejected since Raku looks up to her as an older sister.

Abilities

 * High intellect: Yui is very knowledgeable having been advanced to several grades and years until graduating by the age of 15. Furthermore, Yui was granted with a teacher's license.
 * Great leadership: Yui managed to form a unified Char Siu faction during her reign whilst maintaining its stability.

Weakness

 * Sleepwalking: Yui has tendency to walk into Raku's room when she's half-asleep.
 * Severe overwork syndrome: Yui will faint abruptly if she overworks, with symptoms similar to severe fever. This happened regularly (once every 3 months), however Ie stated that the duration shortened since she came to Japan and reunited with Raku. She can recover in one day if she drinks Ie's special medicine. After Raku reconfirmed their bonds, Ie noted that she becomes more spirited and doesn't get tired even after overwork.
 * Singing: Yui is an extremely bad singer and has been tone-deaf since young. However, if she lost her voice partially due to overuse (singing practice), her singing improved to normal level.

Trivia

 * Yui's surname Kanakura means "play music, complete" (奏) (kana) and "Treasure House" (kura).
 * Despite of her surname, she is tone-deaf and cannot sing.
 * During the ending credits starting from Episode 18, Yui made a cameo appearance in a form of a caricature, alongside Mikage Shinohara, Paula McCoy, Haru Onodera, Suzu Ayakaji, Honda and Migisuke Aiba.
 * Despite knowing the most about the promise and possessing the fourth key, Yui doesn't not share the story even till the end. Although she offered to tell Raku Ichijō everything, he decided to find it out for himself if it even mattered to him anymore.
 * Yui had accidentally jammed her key in Raku's locket as a child causing her key to break and the lock to get stuck. Ie, her bodyguard, removes the broken piece from the locket's interior near the end of series.
 * Yui's first kiss was with Raku (whose first kiss was with Yui as well) as kids. In an accident, young Yui fell over Raku and they shared a kiss. As a kid, Raku wasn't aware of the importance and brushed off the event as unfortunate. However, Yui, being older, knew its significance and that was when Yui realised her feelings for Raku.
 * There has been confusion about the real colour of Yui's eyes. There are chapter covers that show that Yui's eyes are purple but there are also volume covers that show that her eyes are green.
 * Despite being the head of much a larger organisation in the series, Yui was seen having fewest work to do, even being able to take other full-time jobs, in contrast to the head of Yakuza (who cannot visit his wife in different country), gang (often mentioned to have business trips), Police Department (rarely seen in his house), or even a confectionary owner (never seen during the whole series). This is confirmed during the epilogue, where she herself state that a Don doesn't have much work to do.