Kakyou

A woman who was friends with Tousen before he became a soul reaper. Though Tousen was attracted to her, she married a soul reaper instead. Some time later, she's killed by her husband when she condemns him for killing another soul reaper over a minor disagreement. Her death prompts Tousen to become a soul reaper to fulfill her dream of peace in the soul society. Her name and face is never revealed in either the anime or the manga. After Tousen's betrayal of the soul society, Komamura begins visiting her simple unmarked grave for advice and reflection.

Tousen reveals during the "Fake Karakura Town" arc that the real reason that he became a soul reaper was not for his friend's dream, but revenge against the soul society which caused her death and gave her killer what he saw as a light punishment.