Soichiro Tachibana is a first-year high school student and a forward for Tokyo City Esperion FC's youth team, wearing the number 28 jersey. He stands 173 cm tall, weighs 65 kg, has blood type A, and was born on June 11. He previously played for the strong Yokoyama Musashino Kekkodan Junior Youth team but transferred to Esperion Youth after feeling his development had stalled, fearing he might become a useless player. He sought a new environment to reignite his growth and pursue a professional career. His football journey started at age four with Tokyo Musashino FC's youngest teams. One year before the main story, watching Esperion's Youth team win the J-Youth Cup final inspired him to try out for the club once his junior days concluded. During Esperion's entrance exam, he was acknowledged as a prestigious forward from Musashino. He passed the physical tests, scored in trial matches, and confided in candidates Ashito Aoi and Eisaku Otomo that he left Musashino due to a long period without personal progress. He earned his place on the team. Soichiro carries himself with a serious demeanor and a strong sense of responsibility. On the field, his technical abilities stand out; he performs a roulette and a cartwheel kick. Early evaluations also noted his tactical understanding as more advanced than some junior peers. After joining Esperion, he roomed with Kanpei Kuroda. Along with Otomo, he supported Ashito Aoi by participating in secret nighttime training sessions. He was named the starting right winger for the season's first official match against Seikyō High School. Amid a series of losses for the B-team, one coach criticized the forwards for not scoring, though a staff member defended him, saying he shouldn’t shoulder all the blame. He later went to dinner with Otomo, Ashito, and Keiji Togashi to help lift team spirits. His parents reside in Tokyo. On a day off, he visited them and brought along dirty laundry. He has a younger sister named Miyako Tachibana.