Best Friend's Brother (Seungjin)

Seungmin was acutely aware that Yeji would never judge him for being gay. Their friendship was built on trust and unconditional acceptance. But the challenge of coming out to his best friend intensified when he considered the circumstances surrounding his sexual awakening-Hwang Hyunjin, Yeji's twin brother, was at the center of it all.

or Alternatively:

Kim Seungmin and Hwang Yeji are best friends, but things take a complicated turn when he falls in love with her twin brother.