A Hentai System in the World of Danmachi - Chapter 55 - 54 - A lot of money.

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

The legendary Qin Chen from the Tianwu Continent accidentally fell into the Martial Domain because of his friend’s betrayal.

Three hundred years later, he was reincarnated on an illegitimate son of the royal palace who had been bullied.

He used his previous life accomplishments, concentrating on his skills, refining the pill, and rising against the sky, rising strongly, and embarking on a shocking journey that shocked the mainland.

- Description from MTL

Kawaki, who was born in the dragon vein of a planet (Altana), first met Umibozu who was traveling in the universe, and his girlfriend, Kouka.Later, he came to Earth by accident and met the teacher who affected his life —Yoshida Shouyou.He also met a group of friends. The most conspicuous among the group of friends is a fool with silver hair and naturally curly hair, a short man with purple hair, and a little devil whose catchphrase is “Not Zura, it's Katsura!”Gintama Doujin, not transmigration.

Ophelia von Aubessec, an Empress ruling over millions gets slain.Regressing back to her body 300 years ago, she sets her sights on getting revenge on the forces who had managed to kill her.By using her knowledge of the future, she builds her own Empire, wins back the lovers she lost, and discovers the secrets of the system she had been provided.---------This is a dark novel and IT IS HAREM. However, it may travel more into a polygamous relationship due to the complications of a harem.There are also R18 scenes sprinkled about, so please read responsibly.