He notched his first stoppage victory with the promotion, as he knocked Ogasawara with a right straight midway through the opening round.
[6] Aitaka faced Devin Pipose at Bigbang 23 on December 6, 2015, in his final fight of the year.
[9] His five-fight winning streak earned Aitaka a place in the 2016 BigBang Heavyweight tournament, held to crown the promotions' inaugural champion.
Aitaka faced -NORI- in the semifinal bout of the four-man tournament, which took place at Bigbang 26 on September 4, 2016.
Aitaka advanced to the final, held at Bigbang 27 on December 4, 2016, where he faced Taichi Furuta.
He won the fight by a second-round knockout, stopping Jitsukata with a left hook in the very last second of the round.
[11] Aitaka made his K-1 debut against Taichi Furuta at K-1 Cruiserweight Championship on November 22, 2017, in the reserve bout of the 2017 K-1 Heavyweight tournament.
[17] Aitaka faced the inaugural K-1 cruiserweight champion Sina Karimian in a non-title bout at K-1 World GP 2019 ～Japan vs World～ on August 24, 2019.
[21] He was awarded a technical knockout victory after just 57 seconds, as Yang was unable to continue due to a shoulder injury.
[22] Aitaka was booked to challenge the reigning K-1 Cruiserweight champion Sina Karimian at K-1: K'Festa 3 on March 22, 2020.
[23][24] Aitaka faced Animal Koji at K-1 World GP 2021: K’Festa 4 Day.2 on March 28, 2021, following a year-long absence from the sport.
[26] Aitaka faced the debuting Satoshi Ishii at K-1 World GP 2021: Yokohamatsuri on September 20, 2021.
[28] Aitaka faced Hisaki Kato at K-1: K'Festa 5 on April 3, 2022, in the reserve match of the 2022 K-1 Japan Opeweight tournament.