Aya Shameshima started out playing youth soccer in 1995 for Kawachi SC. She continued to play for the team until starting high school in 2003 then playing for Tokiwagi Gakuen High school until graduating in 2005.
In 2006, she signed with Tepco Mareeze a team owned by Tokyo Electric Power Company that played in the L. League, a non-professional league, in Japan. She worked for TEPCO's Fukushima Daiichi Nuclear Power Plant while playing for the team. She made 98 appearances for the club from 2006 to 2011 scoring 18 goals. After the 2011 tsunami and earthquake that cause a nuclear disaster the team pulled out of the L. League.
Shameshima moved to the United States to train with the Boston Breakers and eventually made the move a permanent one signing with the team for 2011. She made her first appearance for the team on June 12 as a second half substitute but she made just five appearances for the team. In September that year she moved to France signing with Montpellier playing 18 games for the team. In 2012 she returned to Japan signing with Vegalta Sendai. She was with the team from 2012 until 2014 but appeared in only 6 games but scored 3 goals. Signing for the Houston Dash in 2014 she became the only Japanese international player in the NWSL.
She began playing for the Japanese women's national team in 2008 and competed in the Women's Asian Cup that year. She scored the first goal in the teams 11-0 win over Chinese Taipei at the tournament. The team finished third over all at the Cup that year. She was a part of the team that won the 2010 Asian Games. She started in every game for the FIFA Women's World Cup in 2011 helping the team to be the first Asian team to win the Women's World Cup. Then at the 2012 Summer Olympics she started five matches as the team won the silver medal falling in the final match to the United States. She has made 52 appearances for the team scoring two goals her second coming against Myanmar in the 2010 Asian Cup.
Sameshima is one of the best in the world as an attacking defender. Her time on the international stage and long playing career will help bring experience to a mostly young Houston Dash team. Technically meticulous the left back will be a force for the Dash's backline.