The main character from what we can tell is the Sprinkbok. However, in a story where a star is iced and is part of a puzzle, there could be other characters involved. There might be a villain who iced the star for some malicious reason. Or there could be a group of characters who work together with the Sprinkbok to solve the puzzle of the iced star. Without reading the story, we can only guess about the other possible main characters.
Given the title 'Sprinkbok a star is iced puzzle story', the Sprinkbok is likely a main character. It's not clear if the star is a character in the traditional sense or just an important element in the story. There could be other characters that are not mentioned in the title yet, like perhaps a wizard or a helper character if it's a fantasy story, or a scientist if it's a more science - fiction - like story.
Since we don't know the full story, it's difficult to say. But based on the title, the Sprinkbok might be one of the main characters. And perhaps there could be other characters related to the star or the situation of it being iced.