Shima is a woman whom Miroku promised to marry two years ago, when she was a sickly young woman. She is forced to be the bride of Nushi.

When Sango learns her story, she is angry that Miroku disgraced Shima, but later Shima admitted to Sango that she lied about sleeping with Miroku in order to avoid being pursued by Nushi as a virgin bride. Shima wished them as a perfect match.

(Source: InuYasha Wikia)