Oita

The club was formed as Ōita Trinity in 1994 and advanced through the Ōita Prefectural League and the Kyushu League before finishing as the runner-up of the 1996 National League, resulting in promotion to the JFL. In 1999, the club changed its name to Trinita due to copyright infringement concerns. The same year, the club joined J.League Division 2, the second-highest flight in Japanese football (renamed to its current name of J2 League in 2015) and placed third. The club also placed third in 2000, and despite being in contention for promotion until the final game of the season in 2001, finished sixth. The following year, the club won J.League Division 2 and finally earned promotion to the top-flight Division 1. In 2008, the club won the J.League Cup, the first major title won by a Kyūshū club since Yawata Steel SC shared the 1964 Emperor's Cup.

In 2009, the club suffered their worst-ever results in their seven-year history in the topflight, including 14 straight losses in league matches, which is the current worst record in the J.League since the golden goal system was eliminated. The club even fired cup-winning manager Pericles Chamusca in mid-July. On October 25, the club's relegation was confirmed after being held to a 1–1 draw by ten-man Kyoto Sanga F.C., although the club would have faced relegation anyway as they had outstanding loans from the JFL's emergency fund and league rules prohibit clubs with such loans from participating in the top tier.

During the 2012 J.League Division 2 season, Oita Trinita finished in sixth place, qualifying for the promotion playoffs in the first year of its introduction in Japan's second flight as the club had also paid back all its emergency loans that October. Despite being the lowest seed, Oita Trinita defeated Kyoto Sanga F.C. 4–0 in the semi-final and JEF United Ichihara Chiba 1–0 in the final, earning promotion to 2013 J.League Division 1, returning to the top tier after a 5-year absence This time, however, their top tier stay lasted only one season. In 2015 they were further relegated to J3 League after losing in the promotion playoffs to Machida Zelvia on December 6, becoming the first major trophy winner to be relegated to the third tier. The club immediately gained promotion back to J2 League by winning the J3 League title in 2016. In 2018, after finishing as runner's up in the J2 League in 2018, Oita Trinita gained promotion back to J1. After finishing 18th in 2021, Trinita would be relegated back to J2 League, but in the background of that, the club made a Cinderella run to the Emperor's Cup Final. Just 1 week after the confirmation to be relegated, they defeated defending Emperor's Cup champion Kawasaki Frontale in stunning fashion in the semis; after the game was tied 1 all, Trinita won 4–5 on penalty kicks. They ended up losing to Urawa Red Diamonds in the final, giving the Reds their eighth Emperor's Cup title.

The club will play its second consecutive season at the J2 League on 2023.