Tamayura (YUKI Ringo)

From Hoshikuzuu Scans:

As the only son of a trading firm, Asakura Michitada enters the dormitory at an all-boys school. There, he is put in the same room as his childhood friend and only person he could trust, Tachibana. But for Asakura, their reunion is something of a more complicated nature.

Note: The magazine and tankobon have different versions of the epilogue.