Imaginary Scramble Wiki

Concave Illogical Number: Imaginary Trench
Great Void Sea Battle, Imaginary Scramble - To the Surface, Nautilus!

This is a story a bit before the fifth Lostbelt...
During a Void Space submersion training session in anticipation of the upcoming battle against Kirschtaria, the Nautilus suddenly runs aground on a mysterious object in uncharted waters. During their attempt to escape from Void Space, the crew encounters a castaway who has been adrift on the sea of Imaginary Numbers.
"I'm waiting for you...in the uncharted sea and rainbow dream."
This is the Reverse Side of the World, a realm that has never been observed. Simultaneously the shallowest and deepest pitfall...the closest, furthest underworld in this world.
Who could be calling from the bottomless sea of Imaginary Numbers?

An event in Fate/Grand Order taking place after the events of Yugakshetra. It was released on the Japanese server on November 11, 2020 and on the NA server on October 27, 2022.