After opening two teaser websites with the hints of X and D, we found out that the “D” website was for an upcoming collaboration of Etrian Odyssey and Mystery Dungeon. As it turns out, “X” was announced as Etrian Odyssey V.
The title was announced at the end of Atlus’ Etrian Odyssey NicoNico livestream with the above trailer. While details are pretty vague, the trailer mentions a new world with the phrase “potential for disaster” in English, and concludes by saying the adventure will go to a new world.
Etrian Odyssey V is currently in development. A release date or platform have yet to be revealed.