Koyuki

was a pretty young woman who saved young Miroku's life seven years ago and died protecting children from the war.

History
Koyuki found Miroku lost in a snowy area seven years prior, and she saved his life.

During the story
Miroku encountered a woman who was identical to Koyuki and she took him back to her home, because she claimed that she had already birthed his child. Miroku was shocked to find many children living in her home, and he began to take care of all of them.

Sango and the others eventually find where they have gone, and noticed that the children Miroku had been caring for weren't children at all, but were balls of snow; they deduced that he must have had a spell put on him. Soon Inuyasha broke into the home and Koyuki unleashed a snow beast on him; Inuyasha managed to momentarily get away from it and finds Miroku and snaps him out of the spell.

Miroku's friends work together to destroy the snow demon, and they freed Koyuki's spirit from the demon in the process. It was revealed that Koyuki was the soul of a woman who had lost her life because of the war. After her death, she took in the spirits of children who also died in the war. At some point afterward, the snow demon took over her spirit.

Koyuki Koyuki 小雪