From Shinmakoku Scanlations :

"Please love me, not my big brother."

Company employee Asahi, who suffered a heartbreak a year ago, met with college student Yuu, after he came to his aid when the latter lost his wallet. After numerous meetings with Yuu, Asahi was just getting comfortable with their relationship when he accidentally discovered that Yuu is the younger brother of the man he used to love.

The traces of similarity made Asahi afraid of getting hurt again. He had decided to distance himself from Yuu when he suddenly received a confession.

"I don't care who you loved in the past, but from now on, please look only at me."