When a pair of otherworldly creatures clashed in the skies over the Sea of Japan, following the opening of an interdimensional portal, it captivated the attention of nations along the coast. Scientists Joe and Marie Hayakawa, who were drawn into the portal during the spectacle, later penned the renowned ''Day of Succession'' based on their experiences. Now missing after a subsequent expedition, their twins Ai and Yu embark on a quest to unravel the mystery of their disappearance and the enigmatic Wonderland they studied. Waiting in the decrepit confines of an abandoned subway station, the siblings board a train destined for the unknown realm, where they befriend Lisa Pacifist, a willing companion on their mission to reunite with their lost parents. Together, can this trio navigate the mysteries of the alternate dimension and locate Joe and Marie amidst the unknown dangers that await?