[1] She won her first national title at the Japan Championships in Athletics at the age of seventeen, taking the long jump crown.

[10][3] The 2001 World Championships in Athletics was her first global outdoor selection, but she did not get past the long jump heats.

[1][14] In 2003, she set a national indoor long jump record of 6.57 m (21 ft 6+1⁄2 in) as well as a 200 metres personal best of 23.91 seconds.

At the 2005 Japanese Championships she had the second best long jump performance of her career with a clearance of 6.69 m (21 ft 11+1⁄4 in).

Her rival Kumiko Ikeda matched this, however, and Hanaoka was runner-up by merit of a lesser second jump.

[1] Both represented Japan at the 2005 Asian Athletics Championships, but while Ikeda reached the podium Hanaoka managed only eighth place.

[2][3] Her third international outing of the year was the 2006 Asian Games and she came seventh, while Ikeda won the gold medal.

[21] She competed sparingly from 2007 onwards, failing to reach the top ten at the Japanese Championships after that point.

She was runner-up at the Japanese National Games in 2008, 2009 and 2010 – the latter was her final year of top level athletic competition.