Double B--Blakey and Brighty--are bright and mischievous young schoolgirls. They live with Grandpa Evin. Evin is a science-fiction writer with extensive experience in space exploration. But he kept this secret very well until one day, his two naughty granddaughters discovered his secret and accidentally entered Evin's secret world. They discover that there are so many interesting and incredible children's worlds in this universe.

Follow Evin step-by-step to explore the road. Double B's finally found that there is a wider space and countless friends who can lead them to know the world. Through the fight against the cunning Dragon King and the communication with the beautiful mermaid, Gia, a door is opened for all students; exploring new worlds is so fascinating.