Prism Spectrum

From Attractive Fascinante:

Oomura Yuu's first kiss was stolen by the beautiful Student Council president, Takamura Mitsuya. He later became his executive secretary and his duty was to do whatever Takamura wanted. Both loved cats and were slowly drawn towards each other. As much as Yuu wanted to acknowledge his own feelings, he realised that he might not really knew about Takamura at all. In the end, Yuu decided to follow his heart and reach out to Takamura.