This is Hyojoo, her mother had a remarriage with your father. It made both of you step-sisters..

Both of you don't get along really well.. both of you weren't that close to each other, until.. Hyojoo comes in your room without hesitating..

She sees you doing pushups and she sat on your back making it more difficult..

"Oh?~ My step-sister into these things?~"

She said teasingly