Yukako is a high-school student besotted with Koichi Hirose. She originally tries to kidnap Koichi before being neutralized and eventually starting a mutual relationship with him. Struck with the Arrow by Keicho Nijimura, Yukako is a Stand User who freely manipulates her hair through Love Deluxe.
Yukako is a teenage girl of fine build, 167 cm (5'5¾") tall. She is characterized as especially beautiful (noted by Aya Tsuji[2]), with fine facial features and bodily proportions. She has full, dark, wavy waist-length hair; a mole above her right breast and dark eyes. She also has prominent, arched eyebrows.
Like most characters in Part 4, she is only seen wearing a dark sailor fuku, a pair of leather shoes and socks, while displaying mature taste in casual clothing.
Personality
Yukako is introduced in the midst of a date with Koichi Hirose,[3] initially acting demure and sweet around him. This visage quickly dissipates when she reveals her bad temper and obsession with him, which occupies the majority of her initial role in Diamond is Unbreakable.
Yukako's most recognizable character trait is her obsessive love for Koichi, which she explains as appreciation for men with potential rather than perfect people, whom she considers boring, and admits outright to becoming obsessive about anything she likes. Her love takes an overtly psychopathic turn when she decides to kidnap him and attempt to brainwash him into reciprocating her feelings, as well as forcefully training him into fitting an idealized picture of himself. Upon Koichi's revolt, she goes completely berserk and is willing to hurt, or even kill him in order to keep him for herself. Once she is defeated, and then immediately saved by Koichi in spite of what she put him through, Yukako sees the error of her ways, becoming genuinely infatuated by his heroism, and as such begins to fully respect his privacy and feelings. After beginning a true relationship with Koichi, she appears much more mellow and relaxed.
Aloof and "insanely tough" (as described by Koichi), Yukako is often cold toward people and maintains a steely, unwelcoming expression, except for in the presence of Koichi, with whom she acts sweetly and warmly in an excessive fashion. She is irritable, blunt and prone to lashing out, particularly when something gets in her way. When angered, her left eye also twitches. Yukako frequently and violently uses her Stand, Love Deluxe, against anyone she feels would hurt her chances of captivating Koichi, resorting to lethal force in the worst case. She has also been described as the type of person who lives in her own world and tends not to listen to others, expecting things to go her way and for people to follow what she says. Even when something goes wrong, she tends to blame it on others and refuses to find fault with herself. Despite the insecure comments in her introduction, she has immense pride in her appearance and hair, even threatening to murder Koichi once he damaged her hair during their fight, and again threatening Aya after her Cinderella caused her face to fall apart.
In the anime, she has a habit of referring to herself in the third person. She also seems to have talent in cooking and sewing, and to some extent engineering as she built an electric chair from household appliances.
Yukako may be described as yandere, and arguably may have predated or became the progenitor of the archetype. Araki comments that her personality was designed in reaction to the prevalency of moe perfectionism applied to many female characters, as a statement that someone of any gender should be capable of being frightening or losing their temper.[4]
Yukako's Stand is Love Deluxe, lending versatile, prehensile life to her long hair; enabling her to spontaneously extend it, grasp heavy objects securely, and strike, smother or infect human targets.
Yukako is a classmate of Okuyasu first introduced in the midst of a date with Koichi Hirose. During the date, she confesses her admiration for him but becomes severely aggressive when Koichi dithers in his response. Later, she jealously attacks a girl she believes to be a potential rival.
In response to false rumors muttered by Josuke and Okuyasu in order to put her off Koichi, she kidnaps him; attempting to indoctrinate him and "change him into a better person".
When Koichi resists, she soon threatens his life, forcing him to fight against her. During a tumultuous battle, Koichi heroically saves her life as she accidentally falls off a cliff.
Yukako, still lovestruck, seemed to have learned from her mistake in trying to force Koichi. Unhappy about her unrequited love she made use of the services offered by Aya Tsuji's beauty-enhancing Cinderella Stand, which rendered her into a bewitchingly attractive woman in the eyes of Koichi - for a price and a certain time limit, during which she was to use a special lipstick in order to uphold the "magic", i.e. the Stand's power. The Stand allowed her to grow closer to Koichi, who, after some trials and tribulations, warmed up to her and willingly became her boyfriend.
However, when she forgets to apply the magic lipstick, her face becomes deformed and she flies into a rage at Aya, who grants her a chance for her to return to her original appearance should she be able to pick her original eyes. Yukako has trouble picking the right one until Koichi arrives to her aid and decides that he will pick for her, but requesting that Aya take away his eyes should he make a mistake. Aya, unwilling to take the role of an antagonist, decides to give Yukako her original appearance back. Following this, Koichi and Yukako share a tender moment and the two presumably become a couple afterwards.
Yukako reappears in Thus Spoke Kishibe Rohan - Episode 8: Deoxyribonucleic Acid. She asks Rohan for help, telling him to examine the strange Mao Katahira. However, Rohan claims that she is fine the way she is and leaves, making her angry. However, she could read within Mao when Rohan turned her into a book and gave Mao's mother Mai vital clues into finding the father.
Yukako later tells Rohan about Mai's wedding with her new fiancé.
(The information below derives from a Light Novel not written by Araki. As such, it may or may not be considered canon.)
Yukako was Chiho Futaba's neighbor when they were kids. She helps Koichi find Hanae Orikasa's killer, a student with red marks on his arms. Suspecting the killer might be in the same class as them, Yukako traps their class in the classroom so Koichi could raise the temperature with a word made by Echoes, making the students take off their jackets. Unfortunately, the killer wasn't in there. Several days later, Yukako witnesses the fire of Chiho's home and immediately informs Koichi.
Yukako makes her first video-game appearance in Eyes of Heaven as a playable character. She was confirmed alongside Koichi, Hol Horse, and Jean Pierre Polnareff.
Yukako is of the Stand User Style, but more specifically is she a Mode User, possessing the exclusive ability to Switch Mode. Unlike other Mode Users, Yukako's abilities and moveset do not dramatically change when she switches, nor is her mode one that requires a lengthy cooldown. This means that she is free to enter in and out of her mode as she pleases. Yukako is still a Stand User nonetheless, and as such, she is one of many characters with wildly varied abilities that grant her uniqueness in battle.
Style Action - Love Deluxe: Yukako enters a voluntary enraged state, causing her hair to flare up. While active, all non-DHA attacks become unblockable, her damage receives a boost, and certain skills gain additional properties. In exchange, she is unable to lock on, guard, Sidestep, or Homing Dash. The ability will deactivate when Yukako's stamina empties and can be manually deactivated at any time with another press of the Style Action button. While Yukako can normally trap larger stage objects with her hair to paralyze opponents, she instead gains the ability to pick up stage objects of any size while Love Deluxe is active, even objects she herself has trapped.
Trait - I can't hear you!: While Love Deluxe is active, Yukako is immune to the effects of Koichi's "I hate you!" skill.
I'm already inside your head.: Yukako extends her hair a considerable distance forward. If it makes contact with an opponent, they will have her hair "implanted" on them. While an opponent has Yukako's hair, she is unable to perform any other skill, and can only re-input the same skill. Upon doing so, the opponent is forcibly drawn towards Yukako, giving her the chance to attack first. If Yukako is knocked down, her implanted hair will be nullified. If Love Deluxe is active, this skill becomes unblockable, the range of the initial attack is extended, and the maximum amount of time Yukako's hair can stay implanted is increased.
You dumbass!: Yukako leaps a short distance toward her target if locked on, backwards otherwise, and attempts to body slam them before swinging her hair. If it connects, she grabs and lifts them up with her hair alone before crushing and slamming them into the ground. If Love Deluxe is active, this skill becomes unblockable and the range of both the body slam and hair attack are extended.
Hmph!: Yukako uses Love Deluxe to extend her hair toward specific points in the stage to pull her to, represented by anchor icons. This allows for quick escapes and inversely can be used to get closer to the opponent just as quickly. Certain types of environmental objects, such as lampposts, allow Yukako to stand on them, granting her the ability to recuperate from out of reach of close-ranged attacks. If Love Deluxe is active, this skill executes faster.
That's what I meant.♡So sorry...: Yukako wraps her hair around her head for a short period of time. If an opponent gets too close, the hair automatically moves into the ground as a trap before bursting upward in a large pillar, stunning the target and leaving them open to further attack.
EX - I'm already inside your head.: The skill executes faster and Yukako is invincible during activation.
EX - You dumbass!: The skill executes faster and Yukako gains super armor (or unflinching to enemy attacks) until she lands from the leap. The hair attack will also cause the target to bounce high into the air when slammed down, setting up for further attacks via Flash Canceling.
Trait - My precious hair! It's turned completely white!: When Yukako's health hits zero for the first time, she will be granted half of a health gauge to continue on with. Her hair color turns white, and Love Deluxe becomes permanently active without draining her stamina. Once her health reaches zero once more, Yukako will then fall permanently.
JoJolities
I'm starting to feel a little violent...: Yukako must use her Style Action 3 times. (200 Points)
You should be thanking me.: Yukako must connect "I'm already inside your head." twice. (200 Points)
Don't you understand that love is more important than work?: Yukako must connect "That's what I meant.♡So sorry..." twice. (300 Points)
Koichi belongs to ME!: Yukako must hit something with a stage object while Love Deluxe is active 3 times. (500 Points)
Love is invincible!: Yukako must Retire an opponent while Love Deluxe is active. (800 Points)
Dual Heat Attacks
Solo - Looks like I'm going to have to play rough!: An irritated Yukako wraps the opponent in her hair before effortlessly flinging them around, slamming them into the ground three times before raising them extremely high up into the air and sending them into the ground one more time hard enough for them to bounce.
With Koichi - Invincible Heroine: Koichi uses 3 Freeze to make the opponent heavier, then Yukako wraps them in her hair before attempting to fling them around. Despite struggling with the increased weight of the opponent, she successfully slams them into the ground four times before raising them extremely high up into the air and launching them into the ground one more time hard enough to generate a shockwave.
Araki based Yukako's initial personality and horrific obsession with Koichi off the horror film, Misery.[5]
An image of Yukako from Chapter 350 is featured on the limited edition cover of Base Ball Bear's 2009 single "Breeeeze Girl",[6] as well as on billboards for its promotion.[7]
Yukako is the only playable character in Eyes of Heaven whose voicelines can dynamically change. In her case, all of her skill quotes and battle grunts becoming shriek-like and violent while Love Deluxe is active.