Ikeuchi Mentaro
Ikeuchi Mentaro, the Ultimate Outsider
Kanji: 池内 面太郎 (いけうち めんたろう)
Romaji: Ikeuchi Mentarō
Epithet: "Ultimate Outsider"
Status: Unknown
Age: 27[1]
Height: 182cm[2]
Weight: 84kg[2]
Gender: Male
Affiliations: Nito Style Karate Dojo (formerly)
Seeker Debut: Chapter 1
Image Gallery

Ikeuchi Mentaro (池内 面太郎, Ikeuchi Mentarō; "Mentaro Ikeuchi"), also known as the "Ultimate Outsider" (最強の外敵, Saikyō no Gaiteki) and also as "The Revenger" (復讐鬼, Fukushū-oni), is a 2nd Dan karateka, formerly at the Nito Style Karate Dojo. He entered two Rokushin Kaikan Tournaments, including the no-holds-barred tournament.


Ikeuchi has short, close-cropped hair and is fairly large, being noticeably larger than Kureishi Mitsuyo. His most distinguishing feature are his prominent cheekbones. He also has developed cauliflower ears over the months since the first Rokushin Kaikan National Tournament. After abandoning karate, Ikeuchi stops wearing his gi and instead wears a pair of boxing shorts during his fights.


Ikeuchi Mentaro is a long time practitioner at the Nito Style Karate Dojo; his sensei, Futoyama Baitatsu describes him as his number one student. His karate career has allowed him to meet all kinds of people, including MMA fighter Kureishi Mitsuyo and kenjutsu fighter Mr. Ito. He is also a staff member at a woman's college.


Six months before the beginning of the series, Ikeuchi enters the Rokushin Kaikan National Tournament and successfully makes it to the final eight competitors before being defeated, an unprecedented feat for a non-Rokushin fighter that earns him the nickname of "Ultimate Outsider". However, Ikeuchi is troubled by the gap in strength between him and the rest of the final eight and brings his concerns to Baitatsu, who confirms his fears: Ikeuchi has reached the limit of his ability as a karateka and will not be able to improve from here. As a result, Ikeuchi decides to abandon karate.

Two days later Ikeuchi goes to Shinjaku to meet Ito and discuss his future. Afterwards, Ikeuchi invites Ito to attend his sparring match between himself and Kureishi Mitsuyo in a week's time.

To the shock of both Ito and Kureishi, Ikeuchi demands Kureishi fight him by MMA rules and with nothing held back. During the match, Ikeuchi counters Kureishi's attempts to grapple him with not only karate blows but also by employing counter-grappling measures he developed in the six months since the Rokushin Kaikan National Tournament. However, neither fighter is able to knock each other out and the match ends by point decision in favour of Ikeuchi, who bemoans his inability to knock out the smaller and lighter Kureishi.

When the second Rokushin Kaikan National Tournament is announced with new, no-holds barred rules, it is revealed to the upper ranking members of Rokushin Kaikan that Ikeuchi's decision to move away from pure karate towards a karate/grappling hybrid is partially the reason the tournament rules have changed. 

Ikeuchi is initially reluctant to enter the tournament until he is confronted by his old enemy, Hayakuwa Samato, a Nak Muay, who declares that he will enter the tournament. Unable to sleep, Ikeuchi conducts image training that night, commanding his mental projection, "Blackie", to fight him as first Ito and then Hayakuwa; after defeating Hayakuwa in his image training, Ikeuchi decides to enter the Rokushin Kaikan Tournament. His first opponent is Yamada Kentaro, who defeated him in the previous tournament. Yamada initially holds Ikeuchi at bay with a storm of Brazilian Kicks, but Ikeuchi responds with a flurry of strong blows aimed at his opponent's meridian line rather than at a specific weak point. Since these blows are much more difficult to dodge or parry, Yamada is unable to keep up and is defeated.

Power & Abilities

Even before abandoning karate, Ikeuchi was a formidable fighter, able to make it to the final eight of a Rokushin Kaikan tournament as an outsider. However, despite his first-class power and toughness, his Achilles' heel was his comparative lack of intuition during combat, which meant he would never be able to match the top level of karate practitioners. In response to his mental limitations Ikeuchi branches out his techniques, learning grappling in order to create counter-grappling techniques and shifting the focus of his blows to the meridian line to compensate for his lack of intuition. Kureishi considers Ikeuchi a natural grappler, able to swiftly gain an understanding of grappling even after only six months. Ikeuchi also has an advantage in terms of the amount of damage he is able to withstand because the Nito Style allows blows to the face which most karate styles traditionally do not permit.


  1. Chapter 1 (Seeker)
  2. 2.0 2.1 Chapter 5 (Seeker)


Community content is available under CC-BY-SA unless otherwise noted.