Combat Press ranked him in the super bantamweight top ten between September 2020 and June 2021.
[12] After suffering his first professional loss, Hayashi was scheduled to face Goro Man at Krush.45 on August 24, 2014.
[14] Hayashi was scheduled to face Wei Rui in a Wu Lin Feng and Krush cross-promotional event held on June 4, 2016.
[24] Hayashi was scheduled to face the #1 ranked RISE lightweight contender Keisuke Niwa, in a non-title bout, at Bigbang 33 on June 3, 2018.
Hayashi won the fight by a first-round technical knockout, managing to knock Mizumachi down three times inside of the round.
[27] Hayashi was scheduled to face Rukiya Anpo at K-1 World GP 2018: inaugural Cruiserweight Championship Tournament on September 24, 2018.
[31] Hayashi advanced to the semifinals, where he faced the reigning Krush Super Lightweight champion Yuto Shinohara.
Hayashi knocked Shinohara down twice in the first round, earning him a technical knockout victory under the tournament rules.
He managed to knock Osawa down two more times before the two minute mark of the third round, which earned him a technical knockout victory.
[33] Hayashi was scheduled to challenge the incumbent K-1 lightweight champion Koya Urabe at K-1 World GP 2019: K’FESTA 2 on March 10, 2019.
[36] Hayashi was scheduled to face Daiki Kaneko, in another non-title bout, at K-1 WORLD GP 2019 JAPAN Yokohamatsuri on November 24, 2019.
[38] Hayashi was scheduled to face Shuai Zhu, in another non-title bout, at K-1: K’Festa 3 on March 22, 2019.
Taio Asahisa stepped in as the second replacement opponent, moving up from super featherweight to lightweight.
[40][41] Hayashi was scheduled to make his first title defense against Gonnapar Weerasakreck at K-1 World GP 2020 in Osaka on September 22, 2020.
[43] Hayashi was scheduled to face Vitor Tofanelli at K-1 World GP 2021: Japan Bantamweight Tournament.
[45] Hayashi was scheduled to face the reigning Krush Super Lightweight titleholder Daizo Sasaki at the K-1 World GP 2021: Yokohamatsuri on September 20, 2021.
[47] Hayashi was scheduled to face the former RISE lightweight champion Fukashi Mizutani at K-1 World GP 2021 in Osaka on December 4, 2021.
[53] Hayashi fought a rematch with Fukashi Mizutani at K-1 World GP 2022 in Osaka on December 3, 2022.