Yasuhiro Koseki

Yasuhiro Koseki (小関也朱篤, Koseki Yasuhiro; born March 14, 1992) 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.^[2][3] He hold the Asian record in this event, set in February 2014.^[4]

Yasuhiro Koseki

Personal information
Full name	Yasuhiro Koseki
National team	Japan
Born	(1992-03-14) March 14, 1992 (age 33) Tsuruoka, Yamagata, Japan[1]
Height	1.86 m (6 ft 1 in)
Weight	82 kg (181 lb)
Sport
Sport	Swimming
Strokes	Breaststroke
Club	Miki House
Medal record Men's swimming Representing  Japan World Championships 2017 Budapest 200 m breaststroke World Championships (SC) 2018 Hangzhou 100 m breaststroke 2018 Hangzhou 4×100 m medley Pan Pacific Championships 2014 Gold Coast 100 m breaststroke 2014 Gold Coast 200 m breaststroke 2018 Tokyo 100 m breaststroke 2014 Gold Coast 4×100 m medley 2018 Tokyo 4×100 m medley 2018 Tokyo 4×100 m mixed medley Asian Games 2018 Jakarta 50 m breaststroke 2018 Jakarta 100 m breaststroke 2018 Jakarta 200 m breaststroke 2014 Incheon 50 m breaststroke 2014 Incheon 100 m breaststroke 2014 Incheon 4×100 m medley 2018 Jakarta 4×100 m medley 2018 Jakarta 4×100 m mixed medley 2014 Incheon 200 m breaststroke Universiade 2013 Kazan 100 m breaststroke 2013 Kazan 4×100 m medley East Asian Games 2013 Tianjin 100 m breaststroke 2013 Tianjin 4×100 m medley

Since 2010 Koseki studied at the Nippon Sport Science University, where he first specialized in the freestyle, and only later changed to breaststroke, motivated by Kosuke Kitajima.