Although Lilith had not explicitly said why she left the Shadow World, judging by the timeline of the Black Fog's invasion of the Shadow World, while she was still there, an invasion by the Black Fog should have been impossible.
Otherwise, with Natalie's current strength able to suppress that Black Fog with ease, Lilith would only have had an even easier time of it.
Since there had been no Black Fog invasion, then Lilith's original reason for leaving the Shadow World was not what the rumors claimed. And afterward, Lilith herself had also said that the Shadow World was merely a contingency she had arranged.
Whether it was Lilith or Tanamo of the Succubus race, both of them had left out something crucial.
With Lilith's arrangements in the Shadow World, if the purpose of the Twilight Abyss's existence was to gather the power needed for Lilith's revival, then even if everything arranged among the Succubus race completely failed—or rather, had no effect at all—what she had left in the Twilight Abyss alone would have been entirely enough for her to revive.
Four authorities, plus a separate portion of power and memories. The Succubus race had one share, and the Twilight Abyss had the same. There was even the variable that was Fei Mi.
Putting Fei Mi aside for the moment, if they assumed the insurance among the Succubus race failed, then in the worst-case scenario, perhaps the entire Shadow World would fall into destruction. In that case, the Twilight Abyss, as a collector, could slowly reclaim all the other powers. If the Twilight Abyss failed to play its corresponding role, then as long as the Succubus race remained enduring and prosperous, one day they would eventually gather enough for her revival.
Even that old man they had seen earlier—the lightning