Safu returns to No. 6 after her grandmother's death and finds out about Sion. Meanwhile, Nezumi disagrees with Sion's goals.

The plan to rescue Safu is going as expected. But the further Sion and Nezumi go inside the facility, Sion’s attitude changes dramatically.

Sion and Nezumi have overcome many difficulties to reach Safu. However, Safu has now merged with Elyurias. Meanwhile, the people gathered to celebrate the Holy Day have been attacked by a large number of parasite bees. Will No. 6 survive? And what will be the fate of Sion and Nezumi?