Mitsuri who had explained to Shinobu once that she joined the Corps to find someone stronger than herself that could protect her and make her a wife and maybe a mother someday. And Shinobu's heart broke because she could never do that for Mitsuri.

Shinobu wasn't stronger than the average demon slayer, much less such an incredible Hashira as Mitsuri. If danger came in any shape other than demon, what help could Shinobu provide? She could never be strong enough for Mitsuri. She could never make her a wife, least of all give her a child.

But oh how she wished she could. Hoped that maybe in another life she wasn't cursed with small hands and tiny frame. That she wasn't stuck loving a woman who could never love her in return. But what would that matter anyway? Shinobu had already signed over her life to defeating this demon. Even if Mitsuri could love her, Shinobu could not offer herself. Not knowing she would throw herself into death's arms the moment she found that wretched demon.

So she would spend her life sitting by Mitsuri's side, listening to her gush about handsome, strong men and hoping that in another life she could be that man for Mitsuri.