Deep Impact was the Japanese Horse of the Year in 2005 and 2006, winning races including the Tokyo Yushun, Tenno Sho, Arima Kinen and Japan Cup.

She was also a half-sister of Pacificus, the dam of Narita Brian and Biwa Hayahide, both of whom were named Japanese Horse of the Year.

[2] Koji Maeda, head of North Hills, named the horse Kizuna, which is a Japanese word meaning "bond", after he was touched by the warm words he was given by others around him when he was visiting Dubai for the 2011 Dubai World Cup that was held two weeks after the 2011 Tohoku Earthquake, which coincided with Kizuna just turning 1 year old.

The colt was then moved up in class for the Grade 3 Radio Nikkei Hai Nisai Stake over 2000 metres at Hanshin Racecourse, where he finished third, beaten half a length and a neck by Epiphaneia and Bad Boy.

[4] Kizuna made his three-year-old debut in the Grade 2 Hochi Hai Yayoi Sho at Nakayama Racecourse on 3 March.

Shortly after the race, it was announced that Kizuna had sustained a small fracture to his left hind leg and would be off the track for most of the year.

[11] After a nine-month absence, Kizuna returned in the Grade 2 Kyoto Kinen on 15 February 2015 and finished third, beaten a nose and a neck by Lovely Day and Suzuka Devious with Harp Star in fifth.

In April he started odds-on favourite for the Sankei Osaka Hai but was beaten into second place by the five-year-old mare Lachesis.