Responses
If you're familiar with manga, then you likely know that "big sis" (or "onee-san" in Japanese) usually refers to an older female, but it doesn't necessarily mean they're related. It's similar to how "oppa" is used in Korean. These terms are often used to show respect or affection for someone older, regardless of any actual family connection.
Big sis??? Please don’t be like all the other manhua characters who are in love with their relatives ToT