Bisha's mission was to investigate a specific individual who had committed blasphemy against their god.
Eren's previous conversation with Priest Rok Jahar had unsettled him, as Eren had refrained from initiating any contact with him since their initial discussion. Consequently, Rok dispatched Bisha on a mission to gather more information about Eren.
Bisha utilized the Immortal Plane as a conduit to traverse her world and enter the realm of Anfang. At least that was the plan. However, reality was far different from an ideal scenario.
Her journey through the Immortal Plane was far from straightforward, and she spent an extended period within it before eventually arriving within the Land of the Faithless. Her emergence took place inside the Oni Dungeon, a domain Eren had long since seized control of.
