[3] In October 2024, it was announced that he married MISAKI, the current Shootboxing Women's Atomweight (-46 kg) champion.
[6] Osaki would go on to amass a 7-1-2 (1) record, before fighting Yuya Kosaka for the WMC Japan Flyweight title at Muay Lok 2017 1st.
[11] Osaki advanced to the tournament semifinals, held at KNOCK OUT 2018 cross over on October 7, 2018, where he faced Yoshiho Tane.
Osaki faced the former two-time Krush Super Bantamweight champion Shota Takiya at Rizin 18 - Nagoya on August 18, 2019.
[19] Osaki faced Konesarn Acegym at Norainu Matsuri 6 Shin Kiba 1st Ring on January 19, 2020.
[23] The fight was ruled a majority decision draw after the first three rounds were contested, with one judge scoring the bout 29–28 for Osaki.
Due to measures implemented to combat the COVID-19 pandemic, only a limited audience of 700 people was allowed into the Korakuen Hall, where the title bout took place.
[26][27] Osaki faced the Shootboxing Japan bantamweight champion Kyo Kawakami in a non-title bout at RISE 143 on November 14, 2020.
[28][29] Osaki faced the WMC and WBC Muaythai bantamweight champion Ikko in a non-title bout at RISE 146 on February 23, 2021.
[38] Osaki then faced Sanchai TeppenGym in another non-title bout at RISE WORLD SERIES 2022 Osaka on August 21, 2022.
Osaki knocked Mangkon down three times inside of single round, which forced the referee to stop the contest.
[47] His wish was granted, as he was booked to face Nicolas Rivas for the vacant ISKA Oriental rules World Flyweight (-53.5 kg) championship at RISE 167 on April 21, 2023.
[51] Osaki was able to thrice knock Lahmar down with low kicks in the second round, which resulted in a technical knockout victory for him under the RISE rules.
He beat Tamaru three years prior, by unanimous decision, to capture the RISE Super Flyweight title.
[54] Osaki faced Jaroensuk BoonlannaMuaythai at RISE WORLD SERIES 2023 Final Round on December 16, 2023.
[56] Osaki made his first ISKA Oriental rules World Flyweight (-53.5 kg) title defense against Djillali Kharroubi at RISE ELDORADO 2024 on March 17, 2024.