MTL - Dragon-Marked War God - Chapter 29 no Zuo no Die

This story tells the life of two people, a noble only in name and an older wife from the army, married through a tentative agreement. In the bone-chilling cold, they spend their time hunting, gutting, and cooking by the fireplace. Their daily life passes peacefully. This is the warm love story recounting their daily lives.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

This book is also called “The Unscientific Ninja Master of Sand Ninja Village”.

“Gara, come on!” “When oil is dug, Sand Ninja Village will explode.” Gaara was puzzled. He was outraged. ”

Teacher Mu Feng, shouldn’t hard work mean hard work in cultivation? You always ask me to dig sand and find oil for cultivation. ”

“Scientifically speaking, digging sand is a very good exercise.”

“Just dig hard. If oil is dug, everyone in Sand Ninja Village will have a white cloth on their head. I will be the richest in the world.”

- Description from novelbuddy

agreed. He thought they might just talk, have a few drinks, and that nothing significant would happen. However, she invited him to a hotel, and they spent the night together.The next morning, she told him it was just a one-night stand and that they would probably never meet again. She said goodbye and left. Ronan also decided to treat it like that.The next day, at his college's hosting club, Ronan was given the responsibility of hosting that year's annual function, where they had invited a singer.When Ronan looked up at the singer, he was shocked—it was the same woman he had spent the night with. After checking her history and social media, he formed an impression of her. Every picture she posted was in revealing clothes, bikinis, or almost nude outfits.He concluded that she was just a promiscuous woman, likely driven by lust, and that she had probably chosen to spend the night with him simply because she found him handsome.Understanding this, Ronan decided to focus on his work. That morning, she had made it clear that it was just a one-night stand and nothing more. He would treat it exactly that way and carry out his responsibilities.Protagonist has System---No NTRIt's Harem, with many girls but The Singer is Main Heroine.