Kyà Âko Nagatsuka (, born February 22, 1974) is a Japanese former professional tennis player. She achieved a career-high ranking of world No. 28 on 14 August 1995. In doubles, she reached as high as No. 31 in June 1995.
She won the 12-and-under championships of Japan in 1986, and the under-16 in 1989.
Nagatsuka reached three singles finals on the WTA Tour but failed to win the title in any of them. She did, however, win two doubles titles as well as achieving a further three runner-ups in doubles competition. She reached the fourth round of a Grand Slam tournament twice in singles: at the 1995 Australian Open, where she beat a young Martina Hingis and Amy Frazier, and that same year at the French Open.
Playing for the Japan Fed Cup team, she has a winâÂÂloss record of 2âÂÂ4.
Since her retirement, she has briefly worked as a coach with Akiko Morigami.