Saeki was born in Okayama Prefecture, and in 2005 he won the boys' singles bronze at the Asian Junior Championships. In 2013, he won the men's doubles title at the Austrian International Challenge tournament, and at the same year, he won the men's doubles bronze at the 2013 East Asian Games. He also helps the Japanese men's team to win silver at the 2016 Asia Team Championships. Saeki plays for the Unisys team for seven year, and in March 2017, he announced his retirement.