BNHA OC| The Steam Hero: Brazen Bull

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Literature Text

Basic Information

Name: Mako Kyne (Mah-Koh Kai-n)

Hero Name: Brazen Bull

Personal Description

Birthday: 2 May

Star Sign: Taurus

Age: 16

Gender: Male

Height: 170cm (5’7”)

Weight: 70kg (155lbs)

Blood Type: O

Hair Color: Black

Eye Color: Brown

Quirk: Thermoregular Augmentation


Status: Alive Birthplace: United States Affiliation: West Coast Hero Academy (US.), Transfer Student to U.A. High (JAP.)


  • Father: Marko Kyne

  • Quirk: Thermal Expansion – Marko can increase the size of his body by absorbing heat. Doing so temporarily increases his physical strength. This quirk also makes him fireproof.

  • Profession: Construction Worker/Welder

  • Mother: Alisa Kyne

  • Quirk: Environmental Regulation – When in a closed environment, Alisa can manipulate the environmental conditions such as raising and lowering the temperature of a room.

  • Profession: Yoga Instructor

  • Younger Sister: Alaina Kyne

  • Quirk: Thermal Redirection – Alaina can manipulate the direction and flow of heat. While her body is not truly immune to heat, her quirk allows her to move heat away from or out of her body which makes her appear to be immune to it.

  • Profession: Student (Junior High)

Appearance Mako is a young man of average height with a lean but highly toned physique. He has slightly tanned skin, brown eyes, and black hair styled into a fohawk. His skin is very smooth and hydrated with the exception of his knuckles which have a noticeable roughness as well as a few scars from martial arts training. In addition to his clean appearance, Mako also has a very pleasant smell.

After transferring to U.A. High, Mako wears the standard school uniform with a pair of gray high-top sneakers. He loosens his tie and the collar of his shirt to allow his body to cool down.

Mako’s casual/street wear typically consists of loose comfortable clothing. Usually, he can be seen wearing a thin, black modern haori with a gray cloud pattern over top a loose white t-shirt. Underneath, he wears either a pair of light jeans or jean shorts with a gray belt and his gray high-top sneakers. He likes to wear the haori to appear “cultured” and because it is really comfortable.

After Hatsume developed his hero costume, Mako wears a special control band on his left wrist that can project a holographic screen. This band and holographic screen act as a remote to control his hero suit as well as a digital watch and notebook. Mako is the only person that can interact with the holographic screen while wearing the control band.

Background Mako’s life was rather uneventful until he entered high school. He grew up as a normal kid with a quirk but didn’t think anything of it. Originally, his quirk didn’t add up to much until he discovered his immunity to burning and later his ability to grow stronger by increasing his body temperature.

By the time Mako was in junior high school, he had decided that he would like to try to become a hero. At this time, he still didn’t really know how to use his quirk but had begun training in martial arts. His idea was that he needed to be able to fight and defend people if he was going to be a hero even when he can’t use his quirk. After several years of training in Kenpo, Mako became a black belt just in time to take the selection exam for West Coast Hero Academy.

Mako passed the West Coast Hero exam by excelling in the rescue scenarios. Despite having the least amount of experience with his quirk, Mako knew that he was fireproof. This came in handy as many of the rescue scenarios involved fire rescue. Mako was able to easily save the test victims and did so without getting burned. When it came to combat scenarios, Mako’s martial arts training came through and helped him show off at times defeating several villain robots.

Mako did not attend West Coast Hero Academy for very long. One day after training, he mentioned to his instructor that he had an augmentation ability but did not have any way to activate it or control it. For several months, his training focused on the augmentation ability but to no avail. Eventually, his instructor realized that their school did not have the resources necessary for him to train his quirk. He recommended for Mako to try and transfer to U.A. High in Japan as they had the best resources and facilities to train unique quirks.

After several weeks of letters and emails, Mako finally received a confirmation of acceptance to U.A. High’s hero program. With this acceptance, he was to transfer to U.A. in the winter. He finished his fall semester at West Coast Hero Academy and moved into Class 1-B’s dormitory. U.A. High’s Hero Support Department has designed a special training facility to monitor and train Mako’s quirk.

“Hopefully this place will work out for him.”

Manifestation of Quirk: When Mako was born he had an abnormally high body temperature and the doctors thought that he had a fever. After several attempts to cool his body down, the doctors determined that he was born with a quirk that made his normal body temperature equivalent to that of a light fever. Several years later, Mako touched a hot stove and was not harmed. As he kept his hand on the stove, he began absorbing the heat until his hand became the same temperature as the stove. After this, his mother found him and told him to take his hand off of the stove. When he removed his hand, he tried to turn the stove off but when he pushed the nob to turn it off, he pushed it through the back of the stove. On that day, he discovered that he was immune to burning and that he becomes physically stronger after his body temperature reaches a certain threshold.

Personality Mako has a very easy-going personality but tends to be shy upfront. He has a hard time being comfortable when meeting new people or when in large crowds. This discomfort also stems from his fear of confinement. Despite these discomforts, Mako is perfectly capable of being social and personable in one-on-one interactions or within small groups.

He is a genuinely kind and respectful person but can be socially awkward at times. He is very socially awkward now because he is new to living in Japan and is not entirely fluent on the culture. He isn’t the top of his class but he is a diligent worker and has maintained above average grades.

While Mako is in tremendous shape from his martial arts training, he is a rather lazy person when it comes to daily life. When he doesn’t have to exert himself, he prefers not to. He predominantly only likes to exert himself when training. Despite this laziness, Mako can be very competitive when it comes to physical things like training and cleaning. He has a strong sense of honor and commits himself fully to the task at hand.

Mako is obsessed with personal hygiene due to the heat effects of his quirk. He is constantly worried about smelling bad from sweating, even though he rarely does, and has a strict wash and deodorant routine. He also has a very strict skincare routine due to the potential dehydration that can happen from using his quirk. Because of all of this, Mako is always very clean with smooth skin and a pleasant smell.

Positive: Clean | Diligent | Honest | Kind

Negative: Culturally Awkward | Lazy | Shy | Socially Awkward

Neutral: Competitive | Respectful | Smart | Adaptive

Likes: Coffee | Cool/Mild Temperatures | Ice Cream | Martial Arts | Cleanliness

Dislikes: Monoma | Heat | Hot and/or Spicy Food | Tight Clothing | Poor Hygiene | His Awkward Seat at the Back of Class 1-B

Fear(s): Confinement | Hatsume’s Inventions

Quirk and Abilities

Quirk: Thermoregular Augmentation

Type: Mutation Emitter

  • Aspects of Mako’s quirk that involve burn immunity fall under the category of “Mutation” while others such as his thermoregulatory and augmentative abilities fall under the category of “Emitter.”

Mako’s quirk has conscious and subconscious abilities. The subconscious abilities of his quirk come from his mutation. These abilities cause him to have a higher-than-normal body temperature which registers as a light fever, and also make his body physically immune to burning. His conscious abilities allow him to raise and lower his core body temperature at will. He can raise his body temperature naturally or by absorbing heat from an external source. Raising his body temperature on his own is a slow gradual process whereas absorbing heat allows him to raise his temperature at a very rapid rate. When he lowers his body temperature, he physically expels excess heat. He can do this in a variety of ways but his most common way is to simply exhale it. When Mako’s core body temperature reaches or surpasses 100°C (212°F), he experiences physical augmentation which grants him increasing strength and power. The hotter his body temperature becomes the stronger he gets. When this happens, his skin turns red from the heat and his muscles grow slightly bigger. Mako's sustainable limit can go up to 260°C (500°F) and currently maxes out at ~329°C (~625°F). Mako can only go beyond 260°C for a limited time before he is affected by heat exhaustion.

When Mako reaches high body temperatures, he uses up a lot of stamina. This is less evident in his augmented state but very evident when he is at a normal human temperature. Raising his body temperature without an external heat source also uses up a lot of his stamina. For the most part, the higher body temperatures can be compared to overall stamina and power. Because of this, Mako requires insulation to maintain his temperature as he has no way to do so on his own.

Super Moves:

  • Bull Rush: using the steam ventilation of his suit along with his enhanced strength, Mako charges towards his opponent to deliver a powerful shoulder tackle.

  • Heat Blast: Mako releases a steaming blast of heat from a part of his body by rapidly releasing the core temperature of that body part. Doing this reduces that body part back to normal (human) strength and temporarily weakens it to the point of near or partial paralysis. This weakness is caused by the rapid loss of stamina and power.

  • Burst: Mako releases the entirety of his core temperature as a massive, explosive blast of extreme heat in all directions. Depending on the heat level, this move can potentially disintegrate objects within close proximity of the blast. Doing this reduces his entire body back to normal (human) strength and temporarily weakens him to the point of near or partial paralysis. This weakness is caused by the rapid loss of stamina and power.

  • Thermal Compensation: Mako redistributes heat throughout his body. This is usually done when he loses a significant amount of heat from part of his body or when he can only heat part of his body.


  • Immune to Fire and Burning

  • Ability to Regulate Body Temperature

  • Ability to Absorb and Release Heat

  • Never Gets Sick due to a Constantly High Temperature

  • Super Strength/Power

  • Ability to Burn/Melt Objects


  • Nervous System Elicits a Pain Response to Acids even though there is no Physical Harm

  • Acid can damage his suit

  • Can experience Heat Exhaustion and Dehydration from Overuse

  • Raising his body temperature on his own is a slow gradual process as opposed to rapid absorption

  • His body Temperature cannot be hidden from Thermal Vision or Heat Seeking

  • His body Temperature becomes too hot to safely interact with others physically

  • Surface Temperature of his costume is still Hot after releasing heat and can only be cooled gradually unless an external cooling source is used.

  • Extremely hot temperatures can (potentially) melt the ground beneath his feet

  • Rapid Release of heat Causes Temporary Weakness/Paralysis

  • Long Term Augmentation burns through Mako’s stamina leaving him extremely weak when he returns to a normal (human) temperature

  • Weaknesses against Cold or Cooling abilities or any disruptions to his suit and/or insulation

  • Extreme temperatures can only be maintained by the insulation of his suit

  • Mako’s suit makes noise as steam is released and it has a light hum from its Steam Conversion Device

Other Abilities: Mako is a black belt in Kenpo and is also a highly skilled grappler. Over time, he has shown himself to be an adaptive fighter as he adopts a variety of fighting styles and techniques into his combat repertoire. He has heightened instincts and a high endurance from his martial arts training.


Speed: 4/5

Strength: 5/5

Power: 5/5

Control: 3/5

Intelligence: 4/5

Cooperation: 3/5

Leadership: 2/5

Will: 5/5

Stamina: 3/5


Lighter: Mako secretly carries around a small lighter to use as a heat source for his quirk when he does not have access to any other heat sources.

Brazen Bull Concept Art:

Brazen Bull Steam Prototype

Brazen Bull Prototype: The Brazen Bull Prototype is a massive 243cm (8ft) tall, Minotaur looking, tank of a suit. It has a large water heater on the back as well as two jets on the forearms. The head of the suit resembles that of a minotaur’s with an open mouth that acts as a visor. The suit is designed with hydraulics so Mako can maneuver it as it weighs in excess of 227kg (5000lbs). This is Hatsume’s first successful creation to withstand Mako’s quirk. It is made from a tungsten-like material that can withstand extreme heat while also insulating it. The water heater on the back is used to produce steam which is circulated throughout the suit. The hoses on the arms are meant to fire boiling hot water at targets. As the internal temperature of the suit continues rising, Mako can absorb the heat for his quirk. This works as an endless cycle as long as there is water and steam.

This idea was quickly scrapped as the suit was too massive and cumbersome to wear and transport. Its massive size was counterproductive to Mako’s augmentation. It also had poor ventilation and very limited vision.

Brazen Bull Nano (Baby Bull): The Brazen Bull Nano, also known as the “Baby Bull” by Hatsume, is a much smaller suit that is made out of a space grade, heatproof, memory steel that can expand and contract with Mako’s body. It has internal and external ventilation systems to allow steam to flow through it. The internal system allows Mako to delay the steam’s contact with his body so it can be super-heated. The external system is used to relieve the internal pressure of the suit.

The body portion of the suit can be stored in a flattened dormant state for easy transport. When Mako wishes to activate the suit, he can do so with a holographic remote that is projected from a special control band. This remote is also used to control the functions of the suit.

When the suit is activated, it resembles plated armor with an insulative, form-fitting, material that covers Mako’s neck and head. He completes the suit by attaching a facemask that resembles a bull’s head as well as a horned helmet and a Steam Conversion Device. The facemask is used to draw in safe breathable air as Mako’s quirk heats the air around him making it hard to breath. It also has a vent to release steam which is mostly for aesthetic purposes. The helmet is also primarily used for aesthetic purposes but it does protect Mako’s head. The Steam Conversion Device is a backpack-like device which draws in hydrogen and oxygen from the surrounding air to produce steam. The armor-like qualities of this suit can grant Mako with a limited degree of protection from light firearms.

Mako can add small hose cannons to his forearms which he can control with the remote. These cannons can be used to fire pressurized steam at targets. They can also be used to convert the steam into water which can be used to put out fires, etc.


Itsuka Kendo: Close/Romantic | Good | Supportive | Competitive

Mako has had a crush on Kendo ever since he transferred to U.A. Being the class representative, Kendo was the first student to introduce themselves to Mako. In short time, as Mako became more acclimated with Class B, he and Kendo grew closer. They have similar personalities and interests outside of the classroom and have developed a close relationship. They are technically at a level to be considered dating but neither of them have acknowledged it. This is ironic because many of the things they do together can be considered "dates." As martial artists, Mako and Kendo are quite competitive. They enjoy sparring with each other to sharpen their skills and hang out. Overall, Mako is very close to Kendo and trusts in her leadership and companionship.

Pony Tsunotori: Close | Good | Supportive

Aside from Kendo, Mako is also very close to Pony. Their friendship hit off from the start as Pony is also a foreign student from the United States. Pony often helps Mako to not feel homesick. Mako often tries to help her with Japanese as she sometimes misunderstands words and phrases. Mako hates it when Monoma tells her to say mean things to Class A. Pony likes to tease Mako for copying her because he wears a horned helmet with his hero costume. Overall, Mako gets along extremely well with Pony and it is safe to say that she might be one of his best friends at U.A.

Tetsutetsu Tetsutetsu: Good | Supportive | Competitive

Mako and Tetsutetsu have a unique friendship that is very competitive. When training their quirks, Mako and Tetsutetsu often spar with each other to improve Tetsutetsu's durability and Mako's stamina. Outside of the classroom, Mako is good friends with Tetsutetsu as they are dorm neighbors. Despite all of this, Mako is not a fan of how loud and overexuberant Tetsutetsu can be. Overall, Mako has a good and supportive relationship with Tetsutetsu.

Mei Hatsume: Good | Supportive | Exploitative

Mako has a relatively good relationship with Hatsume. He has trusted her entirely with designing support gear for his quirk and is always impressed by her ingenuity. While he is very supportive of Hatsume's work, he is also fearful of it. Due to Mako's body being fireproof, Hatsume likes to test her new "babies" on him. Despite her exploitations, Mako has a good and supportive relationship with her albeit a bit cautious at times... Realistically at all times.


  • Mako can speak Japanese fluently but he can’t read or write it.

  • Being new to Japan, Mako often gets lost and has no sense of direction since he can’t read any of the Japanese signs. Because of this, he often gets rescued by his classmates which embarrasses him.

  • Mako is the only member of his family in Japan, the rest of his family remained in the United States. Despite this, he maintains communication with his family.

  • Mako has a habit of exhaling steam from his mouth whenever he is stressed or flustered.

  • Mako’s quirk causes him to have a very high metabolism.

  • Mako’s quirk is very uncomfortable due to the heat.

  • Despite being relatively immune to heat, Mako despises it with a passion. He prefers cooler or milder climates.

  • Despite his Hero Name being “Brazen Bull,” Mako’s suit is not bronze.

  • Mako’s sparring is different with Tetsutetsu and Kendo. When he spars with Tetsutetsu, it’s serious and quirk oriented whereas with Kendo, it’s more of a fun pass time or “date.”

  • Despite his dislike of heat, Mako likes to drink coffee.

FULL ORIGINAL Written Template: © ThePirateHunter

Boku no Hero Academia: © Horikoshi Kohei

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