Rui Osako

High school football

Having played football for children's teams Taniyama SSS and FC Sousarle, Ōsako enrolled at the Kamimura Gakuen Junior High School before moving on to the renowned football school, Kamimura Gakuen High School. Settling immediately, he played a key role in his freshman year, with manager Maki Takemoto stating that if Ōsako hadn't joined the team, teammate Shiō Fukuda would not have achieved the success he had - with Fukuda going on to join German side Borussia Mönchengladbach. In his second year at Kamimura Gakuen, he represented the high school at the 2021 All Japan High School Soccer Tournament, however they were surprisingly knocked out in the first round by the Teikyo Nagaoka High School of Niigata Prefecture. This defeat motivated him, and he would later state "I never want to feel like this. I'll become more desperate, I'll be more greedy to win, and I'll definitely win in the end. I don't want to feel like this." The following year was a better one for Ōsako; having trained with the under-18 side of J1 League club Cerezo Osaka in early 2022, Kamimura Gakuen would go on to beat Cerezo Osaka in the playoffs of the Japan Club Youth Championship, earning promotion to the under-18 Premier League. He was named captain of the high school team, and helped them to the semi-finals of the 2022 All Japan High School Soccer Tournament, where they were beaten by eventual champions Okayama Gakugeikan High School 4–1 on penalties after a 3–3 draw.

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Ōsako was first called up to the Japan under-15 side in March 2019 as part of the "04 group" - players born in 2004 - in preparation for the 2021 FIFA U-17 World Cup. He featured at the Torneo Delle Nazioni, hosted in Italy in April 2019, playing in four games and scoring in Japan's 5–3 win against Turkey as Japan went on to lose to Mexico in the final. In June 2019 he was called up to the squad again ahead of 2020 AFC U-16 Championship qualification in September of the same year. He established himself as a key member of the team, and was named captain for the qualification tournament. He scored once against Malaysia as Japan finished top of their group, however due to the COVID-19 pandemic, the 2020 AFC U-16 Championship, as well as the 2021 FIFA U-17 World Cup, was cancelled. He was called up again in November 2019 for a tour of Spain the following month.

Club

As of 23 March 2026.

Ōsako was born in Kagoshima City in the Kagoshima Prefecture of Japan, where his parents ran a ramen restaurant in Taniyama. It was at this ramen restaurant that Ōsako began to play football, as he would often play with people from his neighbourhood who came to visit the restaurant.