I Worked Myself to Death and Reincarnated as the Queen of His Majesty, Who is Younger than Me!
This is a really original take on the isekai genre! The fact that the previous owner of the body wants to helps her as a ghost, plus the fact that the king knows she's a transmigrator from the start... It's a really cool take! Re-reading this and it's even better than I remembered!! The bond between Emi and Emilia is sweet and strong, the prince is an interesting character with a soft and shy side, the protagonist is not the usual hair-headed and useless princess. It's truly an underrated gem, I loved how the romance was one of the main points but not the only plot point, and how we see the fate of Emilia (the body's previous owner) and it's a big part of the plot. The parts where she crafted cosmetics was cute as well!! I really like the male lead as well. I thought it was going to be a classic yandere guy but he's actually so good!!
Heart Throbbing Conqueror