Eleven-year-old Naho resides with her father and two-year-old brother Jun, who she has to care for since their mother passed away after Jun's birth. Naho can't help but feel frustrated as she would rather spend time with friends, but her responsibility is to Jun. One day, a strange man approaches Naho wearing a long coat and carrying a large suitcase. He goes by the name "Kotaro the Dreamball Dealer" and offers Naho an escape from her mundane life to a world of dreams, but odd occurrences begin to happen to her after their meeting. Naho ventures into new worlds, enjoys time with her pals, and even reunites with her late mother and father. However, her emotions are unsettled as she suddenly finds herself in Jun's dream, leaving her perplexed. She questions her true heart's desires and contemplates what to ask Kotaro.