| Seiko Yamamoto | |
| Native Name: | Japanese: 山本 聖子 |
| Birth Date: | 22 August 1980 |
| Birth Place: | Kawasaki, Kanagawa, Japan |
| Height: | 5 ft 5 in |
is a Japanese wrestler and submission grappler. She is a four time World Wrestling Champion, two time Asian Wrestling Champion and an ADCC Submission Wrestling World Championship medallist.[1]
Her father is Ikuei Yamamoto, who also competed in the Olympics as a wrestler. Her older brother is mixed martial artist Norifumi Yamamoto. Her sister Miyuu Yamamoto is female wrestler and mixed martial artist who won three world titles and one Asian Wrestling Championship in her career.[2]
In four years from 1999 till 2003, she collected four gold medals at the World Wrestling Championships. Because she lost at the Japan Queen's Cup to Saori Yoshida, she was unable to participate at the 2004 Summer Olympics.[3] In 2007, she got married and briefly retired. In 2009 she returned to competetion, and won a championship at the Poland Open.
In 2013, she participated in the "submission fighting" competitions sponsored by the Abu Dhabi Combat Club. She was under-60kg champion at the Tokyo ADCC trials.[4] She won the under-60kg bronze at the 2013 ADCC Submission Fighting World Championship.[5]
She was a coach with the US Women's Olympic Freestyle Wrestling Team before and during the 2016 Olympics.[6]
In 2006 she married team handball player Hideaki Nagashima and briefly retired. In 2007 they had a son. They were divorced in 2014.
In 2014, she began a relationship withbaseball pitcher Yu Darvish. On 29 July 2015, their son was born.[7] In 2016, Darvish and Yamamoto married. They had four additional children by 2022.[6]