|“||Surpass your limits. Right here. Right now.||”|
Yami is a tall man with a muscular build. He has black eyes and black hair of medium length that is messily combed backward. Additionally, he sports a stubble mustache and beard.
Yami's attire is very simple and consists only of a white A-shirt and black trousers. The trousers have an extra layer of tan leather that covers his outer thighs and down to his knees. The trousers are only supported by a belt around his waist. Yami wears another pair of belts, one of which he uses to carry his grimoire. Lastly, he wears black high boots that cover most of his calves.
As the captain of the Black Bull squad, Yami wears a black banner with the squad's insignia on it. He wears it over his right shoulder and it is attached by two strings to his left shoulder. The banner also has tattered edges, seeming to have been ripped off from a bigger banner.
For the Star Awards Festival, Yami wears a simple robe over a fundoshi, and a twisted hachimaki tied in the front. He also carries an uchiwa. The fan and the back of the robe bear the kanji 祭 ("festival"), and the left lining of his robe has 暴れ牛 ("raging bull").
Yami is normally a very quiet person that only speaks a few words. However, he is also a hot head, who could be easily enraged by something as small as being bumped by another person. Yami also has a penchant for intimidation whether he uses threatening words or physically harms his target. He also tends to immediately go straight for a more physical solution to any problems or confrontations, such as when he destroys a part of the squad's headquarters to calm his subordinates.
Furthermore, he also prefers instilling tough love to his subordinates by giving them dangerous missions. He believes that it is the best way for them to overcome their limits and grow stronger. Yami also does not discriminate people according to their social status or circumstances where he is willing to accept Luck Voltia, Noelle Silva, and Asta to join his ranks, even though he is aware of each of their problems.
- Dark Magic: Yami uses this form of magic to generate and manipulate the element of darkness. He primarily uses this magic by channeling it into his sword. This magic also has the ability to draw in other forms of magic, namely Light Magic, absorbing it into the darkness.
- Reinforcement Magic: Yami uses this form of magic to enhance his physical abilities. It also allows him to make up for the slow speed of his Dark Magic.
- Master Swordsman: Yami has described himself as a magic swordsman. He is highly proficient in swordsmanship; he easily fights on par with Licht, the leader of White Night Eye, with nothing but swordplay in conjunction with his Dark Magic, destroying the surrounding environment.
- Enhanced Strength: Yami is extremely strong, as he easily throws Asta a considerable distance with just one hand. He also has incredible leg strength, shown when he jumps to the top of William Vangeance's Great Tree Misteltein.
- Immense Reflexes: Yami possesses excellent reflexes, blocking Licht's light blades with ease when his subordinates and others could not even react to their speed, and nonchalantly counters the latter without having to turn around.
- Immense Durability: Yami is an extremely durable fighter, being unfazed when hit by Licht's light blades, and emerges completely unscathed at his attempted cave in.
- Enhanced Speed: Yami is very fast, surprising someone as fast as Licht with his speed. When Lotus Whomalt attempts to launch a surprise attack on William Vangeance, despite having to climb a massive tree, he arrives just in time to intercept him.
- Ki: A principle originating from his homeland, this skill allows Yami to use a sixth sense to perceive and react to unseen attacks and persons.
- Immense Magic Power: As a captain of a Magic Knights squad, Yami possesses an immense amount of Magic Power, shown when the anti-birds flee as soon as they realize his presence. This is further proven when the slightest release intimidates multiple people. After Yami blocks and counters Licht, Valtos wonders if the captain could rival the Magic Emperor. Gifso, the High Priest of the Seabed Temple, acknowledges Yami as being too powerful for his game. After watching his squad fight at the brink of death, he surpasses his limits to escape the White Night Eye's dimensional trap, and becomes powerful enough to defeat Vetto. Julius Novachrono states that Yami has grown more powerful after he returns to the kingdom.
- Grimoire: Yami possesses a three-leaf clover grimoire that contains various darkness-based spells.
- Katana: Yami uses a katana in combat. It is from his homeland, the Land of the Rising Sun. It was broken by Vetto durning their first encounter, but replaced with a brand new one afterwards.
- Yami Sukehiro vs. Licht: Interrupted
- Yami Sukehiro vs. Liar, Vetto, and Fana: Interrupted
- Yami Sukehiro vs. Vetto: Win
- Magic Knights Entrance Exam
- Noelle's Magical Rampage
- Rescue the Children Mission
- Captain's Meeting: Finding the Traitor
- Temple Battle Royale
- Invasion of Kiten
- Star Awards Festival
- The Hot Spring Training Camp
- "...In the end... the most important thing about a Magic Knight is... magical power." 「...なんや かんやで... 結局魔法騎士に 求めりれるのは 魔力だ "... Nanya kan'ya de... Kekkyoku Mahō Kishi ni motomeri reru no wa maryoku da"」
- "Surpass your limits. Right here. Right now." 「今 ここで 限界を 越える "Ima koko de genkai o koeru"」
- "Protect whatever is precious to you. One day it'll lead you to protect something else." 「テメーはテメーの護りてぇもん護ってりゃいいさ いつかそれが誰かの為になる "Temē wa temē no mamoritē mon mamotterya īsa Itsuka sore ga dareka no tame ni naru"」
- "This is the first time I've seen royalty that was labeled a failure... If you feel like fighting against it all, come with me." 「王族の落ちこぼれなんざ初めて見たわ ...戦う気があんなら
黒の暴牛来れば? "Ōzoku no ochikoborena n za hajimete mita wa ...Tatakau ki ga an'nara uchi kureba?"」
- "Mr. Destiny, huh? I hate that bastard's guts. Who would even pay attention to him? I'd tear him apart and do whatever I damn well please." 「あーいイいイ運命さんね オレそいつ嫌いなんだわ 誰が言う事きくか ブツ潰してでも 好きにさせてもらうぜ "Āiiii unmei-san ne Ore soitsu kirai nanda wa Dare ga iu koto kiku ka Butsu tsubushite demo Suki ni sa sete morau ze"」
- "I like strong women, ya know? But there's nothing wrong in relying on others sometimes, right? And there's plenty strong people you can trust... among us Magic Knights, don't you think?" 「強えー女は好きだぜ? だがたまには誰かに頼ってもいんじゃねーの? そんな頼れる強ぇーヤツらがいっぱいいんのが オレ達魔法騎士団だろ? "Tsuē on'na wa sukida ze? Daga tamani wa dareka ni tayotte mo inja nēno? Son'na tayoreru tsuē yatsu-ra ga ippai in no ga Ore-tachi mahō kishi-dan daro?"」
- Yami's favorite things are tobacco, coercion, and interesting people.
- Yami's grimoire design is the background for Volume 5's cover.
- Yami is the sixth smartest Black Bull.
- Yami is the most muscular character.
- Yami is the tenth smartest captain.
- Yami ranked second in the first popularity poll.
- Yami means "dark, darkness" in Japanese, a reference to his magic and personality.