Kimi Dake ni Ai o...

It's a cause for celebration: the lovely Misa has decided to marry her sweetheart Satoshi. Former schoolmates attend the wedding ceremony. But not all of them are unconditionally happy for the couple. Among those is the protagonist of the game, a young man named Akio, who has always looked up to Satoshi and considered him his older brother. Does Akio harbor "forbidden" feelings to the one whom he must now treat as sister?..

[From Moby Games]