嵐の中、5号車のトンネル内に突如謎の黒い歪みが出現した！ これは元の世界につながるワームホールなのか？ 飛び込むべきか？ 危険はないのか？ 優斗（赤楚衛二）たちがたじろいでいる間に、その歪みは消滅してしまう。しかし、一縷の希望を見出した一同は、再び歪みを出現させるため、物理学教授・蓮見（間宮祥太朗）のタイムワープに関する研究内容をもとに、加藤（井之脇海）の先導で過去に戻る糸口を探ることに。しかし玲奈（古川琴音）をはじめ、お腹に子どもを宿す小春（片岡凜）も危険を冒して過去に戻ることに消極的。乗客たちはそれぞれ複雑な思いを抱えていた。
一方、紗枝（上白石萌歌）への気持ちに戸惑いを覚える直哉（山田裕貴）。優斗もそれに気付きつつある中、直哉が思わぬ決断を。
そして、再び歪みが現れて…。衝撃のクライマックスへ！！
Bien que le vortex se referme, Yonezawa fait une découverte électrisante qui donne aux autres passagers l'espoir de pouvoir retourner à leur époque.
During the storm, a mysterious black distortion suddenly appeared inside the tunnel of Car 5! Is this a wormhole that connects to the original world? Should I jump in? Isn't there any danger? While Yuto (Eiji Akaso) and the others flinch, the distortion disappears. However, the group finds a glimmer of hope, and to make the distortion appear again, based on the research on time warp by physics professor Hasumi (Shotaro Mamiya), the group is led by Kato (Mi Inowaki) and goes back in time. In search of a clue to return to. However, Rena (Kotone Furukawa) and Koharu (Rin Kataoka), who is carrying a child in her womb, are reluctant to take the risk of returning to the past. Each passenger had mixed feelings. Meanwhile, Naoya (Yamada Yuki) is confused about his feelings for Sae (Kamishiraishi Moka). While Yuto is starting to realize this, Naoya makes an unexpected decision. And then the distortion appears again... Towards the shocking climax!
