Wishing to prove to Mile that they are not too dependent on her for help, Reina, Pauline and Mavis decide to accept a particularly difficult quest: Finding an investigation team gone lost while exploring the peculiar fluctuations of a nearby forest's monster population. As they enter the forest, Crimson Vow discovers that some powerful creature has settled in the deepest part of the woods and subjugated the local beast people as its servants. After freeing most of the investigation team, they go after their leader, an elf scholar named Cu Leleia, still held captive in a set of ruins being excavated by the beast people...