Dd4eva

Okay all i can remember about this certain manga is that the mc is reborn into the body of a fat villainess who tormented her sister but she ends up apologizing but no one believes in her so her brother and father confine her to a place outside of the main building, but the sister isnt really mad at her she still loves her (isk if its relevant but the sister has on a cast in the first few episodes). longs story short she wants to make a contract with a spirit so she gathers mana and an herb to help mana grow and she ends up losing all the fat and contracts with the wind elemental spirit king. Thats all i can rmb. OH also it has sum to do with demons as to why the mc reincarnate into that villainess body. If you know what this is PLSSS tell me im not gonna be able to sleep until i find it ┗( T﹏T )┛

Can anyone help me find this manga that's been stuck in my head,
All that i remember was there was this scene where the Mc had a dragon horn and was trying to protect the students at the academy he went to from like necromancer or something and in the end all the students helped him, i also think it was apart of some type of test the students had to take cause it was a point system i think? I know it's not a lot to go on but pls help if you know