Just to recap what I remember from this series: you have Shion, who is a genius, who was tossed out of No. 6, a supposedly utopian city, which turns out to be pretty much a despotic authoritarian city-state with no tolerance for dissent, because he helped a criminal named Nezumi escape. Nezumi wants to destroy No. 6, but Shion wants to save it from a potential invasion of odd bees. Meanwhile, Shion’s childhood friend and would-be girlfriend, Safu, is in trouble for questioning how her grandmother died.
Nezume brings Shion to see an old man who was a founder of No. 6, though regrets it. The man then tells Shion about Elyurias, a powerful being who looked over the forest folk. No. 6. burned down the forest and captured Elyurias in order to use her power for themselves. Nezumi is the last remaining member of the forest folk alive. The man tells Nezumi that the song he hears is Elyurias calling for him. He finally gives Shion a data chip with information about the parasite bees, Elyurias, and the forest folk on it. Meanwhile, Inukashi and Rikiga plan to gather information about No. 6’s correctional facility to help Nezumi and Shion infiltrate it to save Safu.
We finally get some background information about No. 6. We don’t really get a lot of information about the parasite bees, other than they’re not really knew, and this old man apparently knows a lot about them. However, when it comes to No. 6, the creators of it appear to have had noble intentions of creating a utopia. However, once they realized that was impossible, they disappeared or arrested anyone who dare suggest or reveal that the city was not the utopia that they claimed it to be. Of course, the ironic part of this is the idea that a utopia would need a prison in the first place, but…
We also learn about this Elyurias, who is apparently the one singing the song that Nezumi and Safu have heard twice now. Why Nezumi hears it seems clear: he’s one of the forest folk. The question is why Safu also hears it. Also, why does No. 6 want to user her as a “sample,” and what for?