Mariko started riding at high school age in the USA. She was qualified for the 2004 and 2008 All-Japan Show Jumping Championship. She is now running her own riding school together with her husband in Ibaraki Prefecture, outside of Tokyo, and is busy in taking care of the her horses, teaching students and training horses for the show-jumping competitions. She has over 10 years working experience in a leading Japanese thoroughbred marketing company which works with Japanese clients in major auction houses, including Arqana, Barretts, Fasig-Tipton, Tattersalls Ltd and Japan Racing Horse Association, and horse racing publications. Mariko has been covering the CX HKIR and AP QEII Cup in Hong Kong for the past 6 years for the Japanese horses and connections.