Rainbow D:
Yuen was abandoned by his parents and taken to an orphanage.
His only support was Yan, who was like an older brother.
Yan also cherished Yuen like his younger brother, but one night, a cruel incident that separates them occurs.

A few years later Yan, who became a yakuza and lived as Aoyagi, visited the facility again.
However, Yuen, whom he reunited with, is different from the boy in his memory. He was a bewitching young man filled with incense -...