Takuya Arima is grieving the disappearance of his father, a historian with a penchant for unusual research.
During summer break, he receives a mysterious package from his missing father, hinting at the existence of parallel worlds and including a device that supposedly allows him to travel between them.
Initially skeptical, Takuya soon discovers the device is real and embarks on a journey to understand his father's research and potentially find him.
The anime follows Takuya as he navigates these alternate dimensions, piecing together the puzzle of his father's disappearance and uncovering the truth behind the parallel worlds.