Taichi Nakanishi, a goalkeeper from Osaka Prefecture, stood out for his exceptionally large physique even in elementary school, reaching 170 cm tall and weighing 70 kg. His football career began at Naniwa Elementary School, where he competed in the 6th All-Japan Boys' Football Tournament. Confidently declaring himself the tournament's best goalkeeper in Genzo Wakabayashi's absence, his team suffered a 5-1 defeat to Nankatsu SC. Tsubasa Oozora scored from outside the penalty area, exposing a technical gap; Tsubasa observed the shot could have been saved with better spiritual focus. Despite this loss, Nakanishi earned recognition as the tournament's third-best goalkeeper among the top 20 players. Representing Naniwa Middle School, Nakanishi aimed for a third consecutive national tournament qualification. Their efforts ended during regional qualifiers with a defeat against Makoto Soda's Azumaichi team, highlighting recurring critical-match struggles. At the U-13 International Tournament, he served as Japan's third-choice goalkeeper and adapted to a temporary sweeper-defender role in training, though his playing time remained limited. Nakanishi attended Tatsunami High School, competing in the National High School Tournament against Kojiro Hyuga's Toho Academy. His team affiliation continued into university football with Toto University SV, as featured in Tecmo's video game series, though his prominence in the main narrative diminished over time. For Japan's youth teams, Nakanishi was consistently a backup. Registered for a friendly against Denmark during the Golden-23 arc, he was not selected for the final Olympic squad. His sole senior international appearance came in a U-23 training match against New Zealand. During the Rising Sun arc, initially a spectator for the Japan-Germany match, he received an emergency call-up after multiple Japanese player injuries, joining reserves like the Tachibana twins, Ryoma Nishio, Hiroshi Jito, and Makoto Soda. This marked his most significant late-career involvement, though his on-field contributions remained minimal. Nakanishi appears across adaptations, notably in Tecmo's Captain Tsubasa games (II: Super Striker, IV: Pro no Rival-tachi, V: Hasha no Shogo Campione) with Tatsunami HS and Toto University SV. In Captain Tsubasa: Rise of New Champions, he is playable as captain of Naniwa MS, combining physical power with unexpected agility. Captain Tsubasa: Dream Team also features him as part of Naniwa MS's squad. His visual trademark involves sticking his tongue to the side while speaking or saving low shots, a possible homage to Peko-chan. Regionally, he is known as Theo Sellers in European adaptations and Borjini in Latin America.