Miitsu Enseirou

Miitsu Enseirou (, Enseirou Mītsu), also known as the hero Heartthrob, is a student at U.A. High School, and a hero who opposes The Organisation.

Appearance
Miitsu has short, shoulder-length hair styled into a wavy bob haircut. Her outfit consists of a red long-sleeved dress that reaches to her knees, trimmed at the hem and sleeves with white fur. Underneath her dress, she wears long, red-and-white striped stockings. She also wears a large red muffler, kept wrapped around her neck.

Being part of three identical triplets, she looks almost indistinguishable from her sisters, Reiji and Meiya.

Name
Her full name is Miitsu Enseirou. Her given name Miitsu (心一) contains the characters mi (心) meaning heart, and itsu (一) meaning one. It references her quirk's power over the heart, and the fact that she is the oldest sister.

Her surname Enseirou 延齢草 is the name for the Japanese white wake-robin, or the shirobana-enreisou (白花延齢草). It is a monocotyledonous perennial flower possessing three petals, referring to the trio of sisters, who work together in threes.

Personality
Rapid 99 consider themselves a hero troupe, acting out of the best interests of society and the safety of innocents, despite the fact that only one of them (Meiya) can actually legally be considered a hero. To this extent, they rival the Organisation due to contrasting internal philosophies, and the latter’s tendency to sow discord and chaos whenever they operate.

Since they have independently taken up the mantle of ensuring public safety and order outside of the reach of heroes, they have more lenient grasp on the black-and-white concept of heroes and villains, going just for targets who have been at the centre of destruction.

Miitsu, the oldest sister, acts as the team leader. She has quite an overbearing and lecturing personality, going out of her way to debate the ethics of quirk genocide and vigilantism in the middle of combat. She acts as the group’s moral compass, maintaining the core values required to justify their vigilante actions.

Quirk
Heartbeat (心動 Shindo): Heartbeat activates whenever Miitsu plays a rhythm on any surface that is capable of sounding out a beat to nearby listeners, by the use of her own body or using another tool (such as drumsticks.) When Miitsu starts a rhythm, the nearby heartbeats of other people are forced to follow that rhythm, usually leading to instant fatigue, a sudden (and dangerous) loss or rise in blood pressure, and fainting, depending on what the rhythm is. Heartbeat 's effects instantly stop if the rhythm played would be instantly lethal to its listeners, including when the rhythm stops completely.

Heartbeat also works on the hearts of deceased individuals, which Miitsu can use to temporarily raise people from the dead, provided they aren’t too grievously wounded or decomposed, and so long as she keeps playing a normal heartbeat rhythm. If the deceased target’s brain or heart has been damaged, they may be revived in a very weak or confused state, or simply cannot be revived at all if the damage is extensive enough. Individuals revived in this manner regain consciousness of their own free will, and as such aren’t under the control of Miitsu herself, but can be killed again by Miitsu at any point if she simply stops playing. They retain their memories wherever possible, and can still use quirks if they possessed any at death.

Miitsu is immune to Heartbeat’s effects, and anyone who isn’t capable of hearing the rhythm (through being deaf or otherwise impaired of hearing, whether on purpose or not) is immune to its effects. Heartbeat works through hearing, but works regardless of the individual is “able” to hear the noise - so long as the hearing of the target is valid, Heartbeat works on that target. This is why Heartbeat is unable to work on people who hear the noise being duplicated (such as through phones or loudspeakers), but the dead, who technically cannot hear, are still affected.

Other Abilities and Skills
Sharp Eye: Miitsu tends to hang back during combat, as the sheer range of space her quirk is able to cover allows her to dominate fights by simply being present. As such, she has developed a keen eye for incoming danger and the ticks and habits of her opponents, and uses this to gain the advantage of her enemies by adjusting her quirk's rhythm accordingly or warning her sisters of incoming danger. Nothing much gets past Miitsu's notice unless it is particularly well hidden or it throws her off in some way.

Equipment

 * Rhythm Sticks: Miitsu possesses a pair of drumstick-like devices that allow her to play out rhythms in the air, negating the need for a surface to play the rhythm on. The mechanism behind these sticks mimics the action of handbells, in which a hinged clapper-like rod beats against the inside surface of the stick, sounding out a rhythm.

Quotes

 * (To Reiji Enseirou) "Dammit, get this grate open!"