The Book of Abbadon - Chapter 56: Reunion

The protagonist of the collapse of the three former civilizations is Dr. Mei. What is the end of logic, the strongest brain, super intelligence, this is the story of the strongest scientist of Honkai with knowledge of the moon becoming the god of science!

- Description from novelbuddy

Fujii Itsuki unexpectedly found himself in Konoha on the night of the Kyuubi rampage.Although it was a dangerous situation Itsuki still survived.His Isekai life was as dull as it gets, he didn't have any talent for being a shinobi nor did he have a system.Itsuki was prepared to live his life as a lazy bum but unexpectedly he received a summons from the Third, only to find out a piece of shocking news.“ Itsuki I have arranged a marriage for you, the other party is Uzumaki Kushina, I hope you will agree to this marriage ”Facing the request of the Hokage, Itsuki could only reluctantly agree while apologising to Minato who died a few days ago.It's not like he wanted to steal his wife but he was threatened into it.'Sorry Minato, But don't worry I will raise Naruko like she is my own child and take care of Kushina well, and never let her feel any loneliness'Itsuki's seemingly ordinary life was turned upside down due to a single event.

Having being plagued by same dream for the past six years, Chu Yanshen discovered a little boy who looked just like him out of the blue. It was only then did he, Chu Yanshen, learn that he had been deceived by the little lass six years ago…

- Description from Novelupdates

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.