Yamamoto, 22, will not link up with the Leipzig squad immediately — he returns for a further season at Red Bull sister club RB Omiya Ardija in Japan's J.League, continuing a loan arrangement that has been the most productive chapter of his career so far.
In 19 appearances at Omiya he scored 10 goals and provided three assists, numbers that convinced Leipzig to act before his Reysol contract — which ran until 2027 — could attract wider attention.
Prior to Omiya, Yamamoto spent the 2025 season on loan at Renofa Yamaguchi in Japan's second division, scoring 10 goals in 33 league appearances. Before that, a brief loan at Tochigi SC in the same division yielded one goal in nine games.
His time at Reysol's first team was limited — 16 J1 League appearances across the 2023 and 2024 seasons — largely because the club sent him on loan to gather consistent minutes elsewhere.
It is a career profile typical of the Red Bull acquisition model: a young, right-footed attacker with a clear goal-scoring instinct, affordable at his current stage of development, contracted long-term, and placed within the network to continue growing before the parent club decides when to bring him in.
Yamamoto said farewell to Reysol with a message that acknowledged the difficulty of his path.
"It was only a short period as a professional — about a year and a half — but I had to face major challenges," he said. "I believe I have grown thanks to those experiences.
"I have now decided to take on a new challenge."
For Leipzig, the €500,000 fee is minimal insurance on a player they believe has significantly more upside ahead of him. Whether that upside eventually arrives in the Bundesliga depends on what he does at Omiya this season.