Kizuna was born in 2010. He is by Deep Impact out of Catequil by Storm Cat.
Kizuna was awarded Best Three-Year-Old Colt in Japan in 2013. Kizuna showed his great turn of foot and captured the memorial 80th running of the Grade 1 Tokyo Yushun (Japanese Derby) with subsequent Japan Cup winner Epiphaneia finishing 2nd. He also edged out Derby winner Ruler of The World to take the Group 2 Prix Niel in a thrilling finish between the two Derby winners. He is by Japanese Horse of the Year and Japanese Champion Sire Deep Impact, and a half-brother to Japanese Best Three-Year-Old Filly and Best Older Mare Phalaenopsis.
Kizuna entered stud in Japan in 2016. In 2023, Songline landed the Grade 1 Victoria Mile and successfully defended her title in the Grade 1 Yasuda Kinen en route to Best Older Filly or Mare in Japan, as well as Best Miler in Japan honors. Also in 2023, Bathrat Leon, who won the Grade 2 New Zealand Trophy in 2021 and the Group 2 Godolphin Mile in 2022, landed the Group 3 1351 Turf Sprint in Saudi Arabia. In 2024, Justin Milano claimed the first leg of the Japanese Triple Crown, the Grade 1 Satsuki Sho (Japanese 2000 Guineas) in a course record time of 1:57.1 for 2000 meters on turf at Nakayama. In 2025, W Heart Bond won the Grade 1 Champions Cup, becoming only the second filly or mare ever to win the race. Also in 2025, Natural Rise captured the Jpn1 Haneda Hai and the Jpn1 Tokyo Derby, the first and second legs of Japanese Dirt Triple Crown.
Among his other best progeny are Akai Ito, who won the Grade 1 Queen Elizabeth II Cup; Deep Bond, who captured the Grade 2 Kyoto Shimbun Hai, the Grade 2 Hanshin Daishoten (twice), and the Group 2 Prix Foy; Sixpence, who won three Grade 2 races: the Nakayama Kinen, the Mainichi Okan, and the Spring Stakes; and Queen's Walk, who took the Grade 2 Rose Stakes and the Grade 2 Kinko Sho and finished 2nd in the Grade 1 Victoria Mile.
Kizuna was crowned Japanese Champion Sire in 2024 and 2025. Kizuna was crowned Japanese Champion 2yo Sire in 2023 and 2024. Kizuna was crowned Japanese Champion Freshman Sire in 2019.