Toaru Majutsu no Index - Volume 13, Chapter 10: Their respective battlefields. The_Way_of_Light_and_Darkness.

Son of a bitch! I just finished this godawful fantasy novel, and now I'm knee-deep in it – as David, the disgraced son of the Solarian Empire's top general! Talk about some twisted cosmic joke. But hold on a damn minute... maybe this isn't all bad. Armed with the knowledge of that trashy plot, I can become the ultimate shadow player, an overlord perhaps. Screw the damsel-in-distress harem too – it's time to pull the strings and become the real power behind the throne. This isekai might be a steaming pile, but I'm rewriting the ending with a little more... Debauchery (wink wink).

Xu Mo, a modern high school student was sent back in time to Jing Kingdom and found herself trapped inside of the body of a princess with the same name.

She had barely recovered when she learned of an unparalleled fiancé and in a daze, they got married. Then the stunning genius physician who normally does not pay attention clamoured to marry her. After that, there was a cold general, a flirtatious lord, a tsundere young master……

As it turns out, this was a male-dominated dynasty. Because the female population was sparse, the entire nation shared wives regardless of rank or nobility. Is it feasible for someone who wants to maintain monogamy in this dynasty?

- Description from Novelupdates

Utsuro no Hako to Zero no Maria, or The Empty Box and The Zeroth Maria, tells the sinister story of Kazuki Hoshino, who is almost madly attached to his everyday life, and his antagonist Aya Otonashi, who suddenly transfers into his class—for the 13,118th time. She majestically announces to “break” him, without paying heed to anyone else around them.

A journey through space and time... a lost soul that will find the answers about the past of a world and the mysteries of an ancient war.

When Adam finished his turn and then was preparing to go home after several hours of work, his team received a fire alert. He didn't expect that he would die following his father's footsteps, but fate had something else in store for him.

Adam died, but he was reincarnated in another world as Aion Kresnik, with his memories intact. Still, an easy life wasn't waiting for him despite the fact that he had a system and the ability to change jobs and make a spiritual weapon change to many forms. The reason for that was the fact that he was the son of a war hero and, at the same time, the son of a war prisoner and one of the last members of a powerful bloodline of mages. A bloodline that was hated by the whole world.

Aion's goals in that world were simple, get rid of the discrimination surrounding his mother and then find out why he was reborn with such a system since he knew that things couldn't be that convenient...