Story following Kuromi as she travels around the world in search of her missing sister, Romina, who makes her first appearance in this anime. In addition to Romina, a number of new characters will appear, including the friends who travel with Kuromi and a member of an evil organization that stands in the way of their journey.

クロミのもとに送られた一枚の写真。 そこには行方知れずになっていたロミナが 写っていた。 「アタイ、お姉ちゃんに会いたい！」 果たして、クロミはロミナと出会うことは できるのか？