Father was a tennis coach Began holding a tennis racquet at age of 1 Considered quitting tennis at age of 9 and pursuing baseball instead Favourite baseball team is New York Yankees Stuck to tennis and began training as 12-year-old at IMG Academy in Bradenton, FL, USA Enjoys hanging out with friends, watching YouTube videos and listening to Japanese music Likes singing for fun when he's alone and at the karaoke Tennis idol is Roger Federer, who won his 1st Grand Slam title 34 days after Mochizuki was born Also admires Novak Djokovic Goal is to become World No. 1 in PIF ATP Rankings

Former World No. 1 junior achieved career-high No. 129 on PIF ATP Rankings in November 2023 soon after reaching 1st ATP Tour SF in Tokyo

Also at 2023 Tokyo, earned 1st ATP Tour win over Etcheverry in 1R after 0-11 start on tour-level and recorded biggest win of career over No. 10 Fritz in 2R after losing first 7 games of the match

Made his ATP Tour debut at 2021 Singapore as WC and Grand Slam debut at 2023 Wimbledon as Q

Owns 68-67 Challenger record (2-2 in finals), winning titles at 2023 Barletta and 2025 Noumea

Ended his junior career with a 119-45 record on ITF Junior Circuit, highlighted by 2019 Wimbledon boys’ singles title, becoming the 1st Japanese player to win a Grand Slam boys’ singles title

Considered quitting tennis and pursuing baseball at age 9 before moving to USA as a 12-year-old to further develop in tennis at IMG Academy