[2] In 2009, Matsui switched to endurance racing following his departure from Toyota, competing in the Super Taikyū Series in a Honda Civic Type R for Tatsuya Tanigawa's BOLD Motor Sports and winning the class title despite claiming only one victory.

[2][5] After claiming one race victory at Sugo during his 2015 campaign, Matsui remained with the team for 2016 to contest what would be his most successful season in the category, taking a dominant victory at Chang (now Buriram) and charging from the midfield at Motegi to emerge as series champion alongside his teammate Tsuchiya, who retired from full-time driving duties at the end of the year to focus on team management.

Despite his performances, Matsui did not move up to GT500, and instead remained with Tsuchiya's team in the GT300 class for 2017, partnered by Super Formula driver Kenta Yamashita.

Alongside Yamashita and fellow Toyota-supported formula racers Sho Tsuboi and Kimiya Sato, Matsui would spend 2017, 2018, and 2019 in inconsistent form, demonstrating exceptional qualifying pace and taking pole positions but more frequently finishing towards the end of the field.

Matsui joined Team Mach alongside professional sim racer Yusuke Tomibayashi for the 2023 season, driving the familiar Toyota 86 MC.