San Kyoudai, Oniichan no Koi

Three beautiful brothers, Lan, Miki, and Su. Although they have different fathers, they are good friends and love each other dearly. Ran, the eldest, feels inferior to Miki, the angelic-looking second son. Miki's best friend, Ai, has a secret crush on Ran. However, he knows that Miki also loves Ai, so he keeps his crush a secret.

(Source: Takeshobo, translated)