Dekiai Onzoushi wa Kotori ni Kyuuaisuru

Kotori, who works as a maid at the Sonoshiro family's mansion, is looking forward to the return of the young master, Aren, from his studies abroad. 15 years have passed, and when she sees him again, he has grown from a sickly, small boy to a handsome, brown-skinned, sexy man!

(Source: Takeshobo, translated)