Birth Coincidence-Akitoya Royalty Au

The royal Aoyagi family and the Shinonome's, living in the same kingdom meet at the birthday party of Aoyagi's first born child and want their children to grow up together, especially Akito and Toya. They all think that being born on the same day with each other couldn't be just a coincidence but a signal. Ena, Akito and Toya always hang out together with their parents and after some time passes, the two boys start catching feelings for each other but can't say this for years, not wanting their love to separate them from being together.
(Credits to IZ_0o0_ZI on Twitter for the book's cover)