Do you mean this one (I'm adding all titles, but it's all the same):
How to Protect the Heroine’s Older Brother; 여주인공의 오빠를 지키는 방법; ; Roxana: The Way to Protect the Female Lead's Older Brother
nah, it's not that one but thank you for replying ╥﹏╥ <3
BTW i FOUND IT THANKS THO IT'S Mire's Corridor
Glad to here you were able to find it!
(๑•ㅂ•)و✧
So once I read a shoujo where the girl had some mysterious power while the guys around her knew it, it had to do smth with butterflies and she during the early chapters she would take her time getting used to her power. It had similar art style as "Golden Time (Josei Historical)". （/TДT)/