31-banme no Ohi-sama

Felia, a country girl from a remote place born to a lord specializing in farming medical herbs, is told that she was chosen as the king's consort. However, she is the "31st" consort, which means that the king will come to see her only on the 31st of the month. Since the 31st day appears only once every three months, it is unthinkable that the king will choose her as the consort. It turned out that the house she was given from the King has a beautiful garden where she could grow vegetables and herbs. She is unique, strong, and sweet to everyone. Many knights become attracted to this extraordinary consort, and soon the king too...

(Source: Kadokawa)