Seal Princess ~Ohime-sama wa Fuuinchuu~

In a fantasy setting world there is a small country sandwiched between great powers. The king is the descendant of an evil king who sealed demon king powers inside his body. The seal has weakened over time, so a ritual is required to strengthen it. The three princesses are the means to perform the ritual and prevent evil king resurrection. They are ready to cooperate and accept any incoming insults.

[From vndbreview]