Documented path
Tanaka was born in Tajimi, Japan and started karate at age 3 before transitioning to boxing at 11. He suffered from Legg-Calve-Perthes disease as a child, which caused bullying, but he trained without breaks. He won four national high school tournaments and trained under former OPBF champion Hideyasu Ishihara at Chukyo High School before turning pro at 18.
Born June 15, 1995 in Tajimi, Gifu, Japan; trained at the Shirokane Boxing Gym; had a successful amateur career including medals at the World Youth and Asian Youth Championships.
Retired from boxing in 2024 due to repeated eye injuries; four-weight world champion and one of Japan's greatest boxers.
Where the conditions came from
Each is placed on a −1 to 3 scale from documented evidence, and the three are never added together. A combined total would rank Kosei Tanaka against other people. Held apart, they explain why this path ran differently from another one—which is the only comparison this project supports.
The marble itself
+2Tailwind
What capability, drive, or early skill is documented in the person rather than their surroundings?
Karate from age 3, boxing from 11. Won four national high school tournaments. Won WBO world title in only his 5th professional fight. Suffered from Legg-Calvé-Perthes disease as a child but trained without breaks. Exceptional early specialization and achievement.
Where it was dropped
+1Tailwind
What money, family standing, network, or permission was already in place before the work began?
Father Hitoshi was a judo black belt and Japanese national arm wrestling champion who ran a udon shop, then worked in a factory. Father learned boxing alongside his son, became his sparring partner, then his dedicated trainer. Athletic father who became a trainer.
The shape of the track
+2Tailwind
What place, timing, institution, or peer group made the next step available?
Chukyo High School — a recognized boxing pipeline in Japan. Trained under Hideyasu Ishihara (former OPBF champion). Manager Kiyoshi Hatanaka (former world champion). Elite boxing pipeline + champion mentors.
A −1 is a documented headwind, not a missing value; a 0 means the sources record nothing notable either way. Annotation confidence: Medium. These are analyst readings of what the sources record, not measurements of merit, talent, or effort. The twenty-two scored dimensions remain available inside the deeper research detail.
What moved through the conditions
This records repeated behaviour or recovery described by sources; it is not a grit or merit score.
A successful-only archive cannot recover all encounters, avoided setbacks, or alternative outcomes.
Strongest documented signals: Dedicated mentor / coach, Direct domain exposure, Elite institution pipeline.
Describes the starting position, not what the person later made of it.
Strongest observed levers: Domain proximity, Started serious reps before 20, Prior reps.
Measures what was present, not whether it was inherited, earned, self-built, external, or mixed.
The timeline below shows the sequence of work and transitions around the selected early milestone. It is evidence of a path, not proof that every step was necessary.
Dominant figure at the top of a field. The tier summarizes documented career recognition through the data cutoff—not Kosei Tanaka's worth or future potential.
Question four · where did the leverage come from?
Each non-zero lever gets a best-supported origin, evidence signals, and confidence. Unresolved is the honest default when the biography cannot distinguish self-built, advantage-enabled, earned, external, or mixed.
One or more documented starting advantages plausibly enabled this lever.
One or more documented starting advantages plausibly enabled this lever.
One or more documented starting advantages plausibly enabled this lever.
One or more documented starting advantages plausibly enabled this lever.
One or more documented starting advantages plausibly enabled this lever.
One or more documented starting advantages plausibly enabled this lever.
One or more documented starting advantages plausibly enabled this lever.
A structural wave is external to the person, even when their position improved access to it.
This is a bounded inference from the current annotations—not a claim about private effort, merit, or the percentage of Kosei Tanaka's outcome attributable to any origin.
Structural luck, Encounter luck, Event luck, Outcome variance can change every arrow in the path. This successful-only dataset cannot observe the near-identical paths that did not break through, so luck stays visible and unscored.
Multiplying capacity documented later in the path. Measures what was present, not whether it was inherited, earned, self-built, external, or mixed.
Access or conditions documented near the beginning of the path. Zero means "no clear evidence in reviewed sources," not "advantage was absent."
Born in Tajimi, Japan to parents with an older brother and younger sister. Father encouraged sports; Tanaka started karate at age 3. Family background beyond this is not well documented in reviewed sources.
Not documented in reviewed sources. No evidence of family boxing or combat sports background.
Tanaka's early specialization was extreme: karate from age 3, boxing from 11, and four national high school titles. He trained under former OPBF champion Hideyasu Ishihara at Chukyo High School, a recognized boxing pipeline in Japan. His manager Kiyoshi Hatanaka, a former world champion, guided his professional career. Childhood Legg-Calve-Perthes disease caused pain and bullying but he trained without absence. He turned pro at 18 and won a world title in just his fifth fight, demonstrating exceptional skill depth accumulated through years of martial arts training.
advantage confidence: Medium · source count: 4 · audit: partial_source_verification · status: subagent_researched_beta