In 2019, Iwabuchi made his first appearance in the Emperor's Cup, scoring an 82nd-minute winner in a 3–2 victory over Iwaki FC in the first round.
[4] Sendai were eventually knocked out in the second round, losing 2–1 to J.League team Yokohama FC, with Iwabuchi playing 32 minutes after coming on as a second-half substitute.
In 2021, he played 25 games and scored 6 goals, as Iwaki were crowned champions of the JFL and were promoted to the J3 League for the first time in their history.
Near the end of the 2022 season in a league game against Tegevajaro Miyazaki, Iwabuchi suffered a cruciate ligament injury which would keep him out of action for at least six months.
After coming on as a second-half substitute, Iwabuchi scored in his first game back in a 5–1 victory for Iwaki over Omiya Ardija.