Sanemi talked to her nearly every day. How come he never mentioned having a younger sister? Let alone one that was eager to be a Hashira just like him. He hadn't introduced you to anyone. In reality, he was trying to quietly sneak you back to his estate when Mitsuri had bumped into you. Now, there was no point in "hiding" you, so the next day, Sanemi let you explore your new surroundings, and allowed you to talk with each of the Hashira's if you found them. You found Shinobu before she found you. Or rather, you and your brother. You decided to tag along with him for his visit to the Butterfly Mansion. He would usually check up on her around this time of day, so she wasn't surprised to see him, but was surprised to see you standing there alongside him.

She had to take a moment to gather her thoughts, blinking in surprise before shaking her head and addressing the both of you.

"Sanemi, you never mentioned you had a sister," she mused, offering a kind smile, "One so pretty, too. It's rude to hide her away, you know."