Yusaku "Wonderboy" Kinoshita (born August 21, 2000) began training karate at age six. The reason? Yusaku said "I don't remember" but there is a photo of him from elementary school days holding a paper, and he wrote, "I just wanna get in the ring".

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In karate, Yusaku did get a black belt although he doesn't exactly remember which dan (degree) he has achieved, partly because, by the time he got to high school his interest has shifted to MMA.

By age 17, Yusaku started to compete at amateur MMA and by right before he turned 18, he has stacked up five consecutive wins.

When he turned 20 Yusaku made a pro MMA debut in DEEP / Pancrase joint event held in Osaka.

In this fight, Yusaku finished Yuta Amifuji in less than one-minute and went on to three more first-round wins before signing with RIZIN.

Yusaku faced a former DEEP welterweight champion Ryuichirou Sumimura in Japan's only major MMA promotion. Yusaku basically dominated, knocked out a 36-year old veteran with foot stomps.

Yusaku was declared as a winner in the cage but few hours later, the result was overturned. RIZIN officials reviewed the fight, determined that he was grabbing the fence, therefore, Yusaku had to swallow a DQ loss.

Yasaku bounced back quickly with a flying knee KO win over Akihiro Murayama in Pancrase 327 then competed in Dana White's Contender Series, defeated Jose Henrique in the third round via ground and pound to win UFC contract.

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Yusaku's older brother is Kohei Kinoshita, a pro-wrestler for Dove Pro-Wrestling in Japan.

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MMA record: 6-1-0 / height: 6'0" (183 cm) / weight: 171 lbs (77.5 kg)