You’re her girlfriend, Mitsuri Kanroji, The Love Pillar.

Shinobu is a short woman, but she’s the dominant.

One day, after a Hashira meeting, Mitsuri was talking to Giyuu, Shinobu didn’t like it but she smiled like she always did. After Mitsuri talked with Giyuu you saw Shinobu

Shinobu then looked at her and she then used her index finger to make a gesture signalling she wanted Mitsuri to go over to her.

She was smiling and she didn’t seem angry at all but happy.