Naruto: The Outsider's Resolve - Chapter 3.28 (087):

A huge scandal rocked the Qi family. Young Miss Qi gave birth to triplets before she was married!

“She had just traveled through time and now she’s doing a cesarean on her dead mother? And the children were still alive! Then, she had barely had the time to relish in her joy before the stupid villagers were going to burn her as a witch? Later, an emperor arrived on his horse and said, “Come with me.” The girl asked, “Why?” He answered, “Help my precious horse deliver her foal!”

Lin Fuyin had only thought of leading a quiet life with her two siblings after avenging her mother. She had never thought of being embroiled in the murder within the royal family as a village girl! Follow Fuyin through her tempestuous journey and as she stands at the top of the Wei Kingdom! The phoenix flaps its wings, about to soar…”

- Description from Novelupdates

In the fantasy world ruled by Matriarchy, Kael of the Ancient Moonstone House, was working as a guild receptionist. Throughout his life, he was protected by his mother and later, younger sister, who was considered one of the highest potential individuals in the Queendom of Elyria. One day, he hears that his sister has gone missing and his family has accumulated debts of over 127 million gold coins to the Bank. The Queen comes to his rescue, paying off his debts and in exchange, he has to marry her five daughters, who each excel in a domain of their own.Having the five imperial princesses and the Queen herself as the backing, Kael has become one of the most protected individuals in the Queendom. Little did his wives know that Kael had another identity. He is the most dreaded yet noble Assassin of the imperial city, “K,” one who hunts down the criminals who escape punishment either because of insufficient evidence or using their connections.Follow Kael's journey, as he navigates his life as the protected figure in the light and protector of justice in the shadows.

I was a good looking prince when I was reborn, and because I could do indecent things as much as I like, I decided to make a harem while traveling with a beautiful female elf~