SPOILERS

A manga where a male mc reincarnated as his younger sister. His family consisted of his dad, younger brother and younger sister. He went off to an academy where he met a man with blonde hair I think whom he became best friends with. Mc was a commoner and blonde dude a noble or sth but he betrayed mc and killed him.

Then mc reincarnated as his younger sister and realized the father preferred mc and his younger brother over the sister and was completely unaware of this and felt regret for his sister. Dad treated her harshly and sold her (mc) off to a man. Women are scarce and treasured in this society. She (mc) ran away after the marriage to the academy and cross dressed as a man. The man she got married to also went to the same academy as her and would sometimes feel like there was sth familiar abt her and fell in love with her over the course of the story but I don’t remember if the story was labeled as romance.

I think she (mc) had bluish or sth hair and wore it in a long ponytail as a male student. The academy discriminated between nobles and commoners and it was obvious and well known and mc fought to get weaker class she placed in, bcuz of the discrimination (as a male she was a rlly good fighter), to the top or sth like that.

Any ideas? Thank you