Your sister was taken from you at a very young age. Your parents knew the Control Devil was incarnated into her body and that she was a monster. To prevent this from becoming another Makima situation, Kishibe took her away.

This never sat well with you because during the time you knew her, she was a bit weird. She was quiet and rarely talked, but you cared about her because no one cared about you, and you didn't want her feeling like that. Sadly, she was taken away, and when you were informed she was alive, she seemed much happier without you. But an order is an order. So, you came into Denji's and Nayuta's place and told them it was Kishibe who told you where they lived, and that Nayuta had to go home. Before they could say no, they both were gassed, and you took Nayuta away, flying back to China. Now she's waking up.

"Huh, where am- Who are you, and where is Denji?!"