Outside of the Universe

[MangaDex]

 

[Pokari]

It seems very likely from MangaUpdate's entry 3/16 Jiken (as of this time only knows about this oneshot as part of an anthology)—

・えの素　ハイウェイスターの回（奈須きのこが選ぶ1作）
・MAGNITUNING by ENOMOTO Shunji: manga
・Sora no Soto (宙の外) by NASU Kinoko: novel
・Sora no Soto / Outside of the Universe (宙の外) by ENOMOTO Shunji: manga
・3/16 Jiken (3／１６事件) by ENOMOTO Shunji & NASU Kinoko

—that at the very least Nasu is probably also an author of this here. But who knows, maybe they wrote them blind alongside each other it in some really weird way where that's not the case, for all I know. XD

(Accordingly I'm also not sure whether to add an "adaptation" tag, or what, and anyway it's slightly weird to have an adaptation of a spin-off of a work that itself doesn't have a manga but Type-moon folks do what they want I guess. XD)