She actually said she needs to rest. She said she's been having some hormonal problems over the last few months and hasn't been feeling well. She says it's possible that she may return to the ring after a long rest. Watanabe did marry her cartoonist husband in January and a lot of female combative sports athletes tend to retire when they get married.
Hisae Watanabe started out as a muay thai kickboxer. Her first MMA match was in Apr. 2002 but it was her win at the Golden Muscles tournament in May 2004 that was televised across Japan on TBS that made her a star. Watanabe was known for her devastating punching power but her weak ground game is what caused her worst losses. Her record was 19-6 with 10 KOs. She almost quit after losing a title match to Smackgirl Lightweight Champ Yuka Tsuji in May 2005.
But she started working exclusively for DEEP and became their Lightweight Champ when she knocked out Satoko Shinashi in Aug. 2006. The beginning of the end came when Watanabe was upset in a non title match by Korean Ham Seo Hee in Feb. 2007. She lost the title to MIKU in Aug. 2007. She had one more fight but maybe she doesn't have her heart in it anymore. She has a lot of flair so we'll all miss that but maybe she'll return down the line. Good luck to her regardless.