The content below is entirely editable.
"Mayu will never be false to Mayu!"
Something of a prodigy, Mayu attends the same college as "Hanabishi-sama" purely by accident. Meiritsu University was chosen for her by her father and she initially thought poorly of it. She is in love with Kaoru because he cheered her up at a party when she was 12 years old. At that time, Mayu's parents informed her that they would be missing her 12th birthday because of business overseas. They gave her a stuffed rabbit as a gift because her father has made a habit of giving her stuffed toy animals as gifts for years. Mayu's parents had been holding a party for their business partners, and no matter what Mayu said or did, her parents simply did not have the time for her. Dismayed, Mayu ran off into the woods, bumping into Kaoru and dropping her rabbit as she fled. Kaoru followed her and tried to cheer her up, but she exclaimed that her parents did not take care of her at all, and that they also did not love her. Kaoru then uses the rabbit (which he named "Ussaa", a contraction of usagi, the Japanese word for "rabbit") as a puppet to cheer up Mayu, telling her that her parents do love her very much, and that even if they do not pay as much attention to her as they should, it's better than having no parents at all, like himself. This left a significant impact on Mayu, and she kept and cherished Ussaa to the current day. Mayu is still very lonely, because her parents are always busy working. She tries as hard as she can to do things that would make Kaoru happy, such as learning how to cook from Aoi so she could make lunch for him.
When we first see Mayu, she is insulting the men of Japan and complaining of her father forcing her to go back to Japan. When she sees Kaoru at the school festival, she pounces on him and kisses him, which causes Tina to go on a drinking binge and Aoi to enter a slight depression. Mayu convinces him to come to dinner and does everything possible to keep him with her until he ends up spending the night with her in her bed. He is chagrined at her behavior, but upon seeing Ussaa in the bed, he remembers their history together and feels a little less upset with her.
Mayu shares a rivalry with Tina, whom she considers uncouth, and whose presence she cannot stand. The two characters are opposites in many ways. Where Mayu is serious, Tina is playful. Where Mayu is uncharacteristically open in her unrealistic desire for Kaoru, Tina is uncharacteristically shy in her (almost) reciprocated love of Kaoru. Where Tina is an American who embraces Japanese culture, Mayu is Japanese and embraces Western culture. When Tina accidentally bumped into her during their first meeting, Mayu reprimanded her in English, while the out-of-practice Tina struggled to recall an appropriate retort in her native language. Even their introductions to Kaoru are mirrors of one another. Kaoru did much to lift Mayu out of her loneliness, while Tina lifted Kaoru out of his own loneliness and apathy following his defection from the Hanabishi clan. In later volumes, Tina and Mayu develop a love-hate relationship and it is Mayu who forces Tina to be more honest with herself and everyone around her.
Mayu's given name (mayu) means "cocoon", a reference to her family owning a silk company.
Mayu has the habit of referring to herself in the third person when speaking.
Mayu did show an act of mentorship when she attempted to take Chika shopping for her very first bra, although this ended in comedic disaster.
Mayu is a gifted pianist, though this is never directly mentioned until the Ai yori Aoshi: Enishi series (she is seen playing a piano in a flashback in episode 12 of Ai Yori Aoshi). This was also shown in the manga when Mayu sought Aoi-chan's help regarding Japanese clothing. Mayu's mother sent her a new designer kimono, but she had no idea how to wear it. Aoi taught her how to dress, as well as ikibana and playing the koto. Mayu was inept at the last two and felt discouraged. Then, Saionji-san appeared to tell everyone that Mayu was a gifted pianist and they convince her to play for them, which she does beautifully.
In the final chapter, which happens four years after Tina has returned to the US, Mayu was shown to have grown into a beautiful woman (possibly another nod to her given name), living in England, although she still bickers with Tina when they met. She has not, however, given up on Kaoru, and visits roughly once a month, causing Aoi some irritation.