Momiiro no Heya to Yoru no Tsubo

When a your royal reached adulthood, there is secretive pink room where he is brought and a rite of passage is performed. The young man is not kept privy to the ritual in advance. On the day of his birthday, our protagonist is brought to the pink room. To his shock, what awaits him there is the sweet scent lingering in the air and a beautiful elf girl bound to a bed. The ritual may start...

(Source: Fakku!)