Shimajirou to Kirakira Oukoku no Ouji-sama

The story centers on Pearl, the prince of the Glitter Kingdom, who is preparing to become king. After he leaves the kingdom to go to Challenge Island, a situation causes the kingdom to lose its precious glitter. Shimajirou and friends set out with Pearl, who lacks self-confidence, on an adventure to find three keys to save the kingdom.

(Source: Anime News Network)