Mayumi Watanabe (渡辺 真弓, Watanabe Mayumi, married name Amagaya (天下谷), born 6 June 1983 in Niigata) is a retired Japanese athlete who specialised in sprinting events.[3] She represented her country at the 2007 and 2009 World Championships.
Her personal bests are 11.44 seconds in the 100 metres (+1.7 m/s, Fukushima 2011) and 23.35 seconds in the 200 metres (+0.4 m/s, Fukuroi 2013).
She retired in October 2015.[4] She is currently the coach of Toho Bank Athletics Club.[1]