Steins;Gate: Heni Kuukan no Octet  

Gate: Octet of Spatial Mutation, STEINS;GATE 変移空間のオクテット

In the Steins;Gate universe, approximately one month after the disappearance of the time machine, Okabe experiences vertigo and reading Steiner. Following this event, he receives a D-Mail from someone named Okabe Rintarou in 2025. This message reveals that the current worldline is in grave danger, even more so than Dystopia or World War III. His mission now is to locate an IBN 5100 and retrieve it from Neidthardt.