Chewing Gum Dagashi - Suppai Budou ni Goyoujinすっぱいぶどうにご用心
This Dagashi is a package of 3 balls of gumwith grape taste. But as the name suggests, one of 3 contains a sour center . The other 2 are sweet and mild. The surprise is that we do not know where is the acid ball and that's what makes a game :)