Koutei Heika ni Narou!

About

While our king was visiting his dying teacher, he found and released a girl sealed in a tree. It seems his teacher had sealed her because she came from the underworld. What he released was just her spirit. To get her body back, he has to find medals that his teacher gave to other kings. Well, he has four commanders to help him do that. He can also get some princesses too, if he want to.

Source: IGDB