It Seems That I've Slipped Into a Different World. Also, My Gender Has Changed. - Chapter 103: Blasting Off, Civil War in the Mansion

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.

After getting betrayed and killed by the only person she’d loved, Miss Shang wakes up in the body of the cowardly crown prince Shang Wuxin, who, due to her own circumstances, was actually a girl cross-dressing as a boy. After inheriting the crown prince’s memories, Shang Wuxin has three things on her agenda:

1. Clean up the house

2. Gather loyal followers and soldiers

3. Get the throne

- Description from Novelupdates