Mayumi

Mayumi is Mahiro's sister and was married to Muramasa for a period of time after he escaped from the Mibu Clan. She was killed four years ago by Chinmei, not Kyo (as Mahiro believes), before which she gave Kyo his sword, Tenrou (forged by Muramasa). However, Mahiro doesn't find out the truth until much later in the story.