Read manga: Oniichan No Koto Ga Suki Sugite Nyan Nyan Shitai Burakon Imouto Dakedo Sunao Ni Narenai No

manga
Summary:

Saya is an average schoolgirl in every way but one; she's got a HUGE crush on her older brother. She's never been able to raise any flags with him (mostly due to her habit of beating him to a pulp whenever she sees him), but one day, she wakes up in the body of a cat that he brought home! Could this be her chance to make her beloved older brother fall for her?