Marry first/do later, love by force, fake brother and sister, marriage, male competition, 1vN, non-c, rebirth and time travel system, princess, soul conversion, teacher-student love
Ashinagara, 4, female but not male, Shura field, the female protagonist is the daughter of the Turkic Khan and Daye's princess. When she was 8 years old, she was brought back to Daye and named a princess.
