List of Famous people with last name Koseki

Yuta Koseki is a Japanese actor and model.

Yasuhiro Koseki is a Japanese competitive swimmer and breaststroke specialist. He won the 100-meter event at the 2013 Summer Universiade, 2013 East Asian Games, and the 2014 Pan Pacific Swimming Championships. He hold the Asian record in this event, set in February 2014.

Momo Koseki is a Japanese former professional boxer. She is a two-weight world champion, having held the WBC female atomweight title from 2008 to 2015; the WBA female atomweight title in 2015; and the WBC female strawweight title in 2017. Koseki has made a record-breaking sixteen consecutive title defenses of her WBC atomweight title.

Shota Koseki is a Japanese professional baseball catcher for the Tohoku Rakuten Golden Eagles in Japan's Nippon Professional Baseball.