Ikemen Oukoku Joou to Shinjitsu no Kiss

Bramble Kingdom is small and peaceful. One day, a larger power begins moving against it, and the protagonist is unexpectedly chosen as queen—not for any conventional reason, but because the country needs one urgently, and she was selected. Her only official duty is to enter a contract marriage to protect the kingdom from annexation. Eleven men from five neighboring countries are involved, and somewhere in the political maneuvering, the possibility of something real emerges.