Iwashimizu plays since 2001 for NTV Beleza club, where she is a regular player.
Iwashimizu already played in the U -18, U-19 and U-20 selections of Japanese women's national team, they played at the Universiade 2005 Izmir for Japan. Iwashimizu completed her international debut for Japan on 16 February 2006 against Russia. She scored her first goal on May 7. 2006 against USA. She played for Japan, all three games at the 5th Women's World Cup 2007 as well as all six games at the Olympic Games in Beijing in 2008 and all six games at the 6th Women's World Cup 2011 in Germany. In the preseason game against Sweden they shot the opening goal, the Swedes could reverse in the second half.
Iwashimizu also belonged to the Japanese squad for the Olympic Games in London. She stood in all six games in the starting lineup and played over the full distance in each case, including in the 1:2 lost against the USA finals and won the silver medal with her team.
- World Champion at the FIFA Women World Cup 2011 in Germany
- Silver medal at the 2012 Olympic Games