Daiki Iwamasa

Iwamasa was the captain of the Japan team that won the 2003 Summer Universiade held in Daegu, South Korea, where he scored a goal in the final of the tournament. He received the first call-up for Japan national team in 2008 by newly appointed coach Takeshi Okada. On 10 October 2009, he made his international debut in a friendly match against Scotland. He was also one of the final 23 Japan national football players participating in 2010 FIFA World Cup in South Africa although did not play any minute during the tournament. After the 2010 FIFA World Cup, in January 2011, he was selected Japan for 2011 AFC Asian Cup by new manager Alberto Zaccheroni. At the 2011 AFC Asian Cup, he played in four matches and Japan was the eventual champions. He played eight games for Japan until 2011.

Iwamasa was born in Suo-Oshima, Yamaguchi on 30 January 1982. He was educated at and played for Iwakuni High School and Tokyo Gakugei University before turning professional.

Kashima Antlers

Iwamasa started his professional career at Kashima Antlers where he later became one of the club's longest serving players. He became a regular player at center back from late first season. The club won the title in J1 League for three consecutive seasons (2007–2009) which is the first time in J1 League history. He was also elected in the J.League Best XI for three consecutive years. The club also won 2007, 2010 Emperor's Cup, 2011 and 2012 J.League Cup however his opportunity to play decreased in 2013 and he left the club end of 2013 season.

BEC Tero Sasana

In 2014, Iwamasa moved to Thailand to join BEC Tero Sasana which he helped the club to win the 2014 Thai League Cup where he scored a goal in the final that ended in a 2–0 victory.

Fagiano Okayama

In 2015, Iwamasa returned to Japan and joined J2 League side, Fagiano Okayama ahead of the 2015 season.

Tokyo United

In 2017, Iwamasa moved to sixth tier Regional Leagues side, Tokyo United. He retired at the end of the 2018 season.

Jobu University

After retiring as a player in 2018, in 2021 he became manager of Jobu University's football team.

Kashima Antlers

For the 2022 season, Iwamasa became the assistant manager of Kashima Antlers and took charge of a number of games whilst new manager René Weiler awaited entry to the country due to COVID-19 quarantine restrictions. In August 2022, it was announced that Iwamasa would be promoted to manager of Kashima Antlers following the departure of Weiler. The first game in the charge was 2–0 home win by J1 League against Avispa Fukuoka on 14 August 2022. But the in the nine games after. only one win against Vissel Kobe in Emperor's Cup, the team was knocked out by second-tier team Ventforet Kofu after defeat by 1–0. Ending the season in fourth place, three points behind of the AFC Champions League slots occupied by Sanfrecce Hiroshima. The 2023 Season starts with an away victory over Kyoto Sanga by 0–2. The first match at home was a defeat against current runners-up Kawasaki Frontale by 1–2. Following this, the team collected mixed results in the Emperor's Cup. They were knocked out by the defending champions, Ventforet Kofu for a consecutive season after a 1–1 draw, the team lost 10–11 in the penalty shootout. Following the end of the campaign, Antlers won the last match of the competition against the relegated team Yokohama FC.), ending the aspirations for qualification to AFC Tournaments after a 3–1 defeat to Vissel Kobe. On 5 December…

Club

As of 1 January 2015

International