Shirayukihime no Musume to Shitsuren Ouji: Onee Joou to Shirayukihime Gaiden

Emilia, the daughter of Queen Snow White, falls in love with Luka, a prince from a neighboring country who was in love with Snow White! The black-hearted prince, who had given up on on love after being rejected by Snow White, is now being aggressively courted by the innocent girl! The child of the pure-hearted king and the innocent Snow White turns out to be quite the little princess! It's the beginning of a new pure-love story with an age difference! (Source: Pixiv, translated)