Henkyou No Mahou Kusushi - Jiyuu Kimama Na Isekai Mono Zukuri Nikki summary:

Me, who has mastered the game profession of "magic medicine doctor," was reborn in a miserable world where the only medicine available was a grotesque recovery potion!Reincarnate as a child of a noble family and save the world by secretly improving magic potions. If you create not only medicines but also various other things, you may be thanked by your cute little sister and everyone in the territory!