This manga was written by Kurumatani Haruko. The story here is basically love between siblings, Doumoto Chihiro and his sister Ami. It isn’t the first nor the last manga you will read where siblings fall in love with each other and then they find out that they aren’t related by blood. Here you see that almost in the beginning of this manga.
Chihiro knows that they aren’t related, and Ami doesn’t. Yet she falls in love with her brother and tries to fight against it. Instead of saying something to her (he doesn’t want to hurt her), he sabotages every chance she has for a relationship. He also makes her self esteem go down by dressing up as a girl even at school, just to show her that he is prettier than she is.
The story wouldn’t be complete if there wasn’t a guy who was jealous of what they could have and who figures out everything and then tries to mess up with everything.
Basically there is a heroine that is physically strong but everyone does to her what they want, the “brother” that seems to feel like he owns her and she has to be his and a “villain” that plays with them because he’s frustrated with his own situation. Pretty boring and predictable, with a really rushed ending, in my opinion.