Tsun Ane Princess Emiria to Nangoku Oukyuu Kozukuri ~Nakadashi nante Namaiki yo! Aka-chan Dekiru made Yurusanain Dakara!~

The main character is an ordinary student.
One day, he is kidnapped by someone and when he wakes up, he finds himself surrounded by 3 beautiful women in a luxury palace.
They turn out to be princesses in a small tropical country and ask for the childmaking to be regarded as the official couple.

[From DLsite English]