June 1983. The tragedy is finally over—at least, it was supposed to be. Years later, Rika meets up with her old friends for a club reunion...then once more awakens in June of 1983 with no memory of why she has returned. And now that Hanyu is out of the picture, Rika must face the tragedy alone...

When his mentor is injured, novice linguist Hakaba is appointed to take over the professor's research in the Netherworld! Though Hakaba has studied the languages of werewolves, lizardpeople, and other Netherworld races from afar, this will be his first field experience coming face-to-face with those so many of his fellow humans have dubbed "monsters." Guided by Susuki, the professor's half-werewolf daughter (?!), Hakaba begins his quest for a greater understanding of the ways people of the Netherworld communicate-even if it does get a bit...hairy at times...!

Hakaba’s diverse traveling party, made up of half-werewolf Susuki and lizardfolk siblings Kashuu and Kekuu, welcomes its newest member, the minotaur Moo. Struggling to communicate through a series of wild gestures, guttural grunts, and the gnashing of teeth, Moo eventually gets his point across in Old Werewolf—a language that is new to the linguist at large! Discovering the varied ways Netherworlders communicate grants Hakaba fresh insights into how different species think and interact. And, unbeknownst to him, his human tendencies are being scrutinized just as closely?!

With winter weather fast approaching, Hakaba finally arrives in Utatsu to continue his linguistic research. The diverse residents of the town—and their flexible notions of “private property”—provide ample opportunity to study Netherworld culture and communication from the comfort of his “own” home. Despite having the best intentions, Hakaba must be mindful that human biases don’t negatively affect his attitude toward his new comrades…even when they decide the walls of his newly restored dwelling would make a perfect snack!

Treacherous roads force Hakaba and his party to wait out the winter in the mountain village. The extra time affords Hakaba the opportunity to puzzle out the lamias’ rhythmic tap language as well as decipher the meaning of the professor’s recently uncovered papers. Though only a few scraps could be recovered, the professor’s sense of foreboding and urgency are apparent. If humans cannot understand the Netherworld, the threat against his loved ones may become dire, instilling a fear that hits Hakaba closer to home more than ever before...

Hakaba's small party's travels continue, and the next stop on their journey is sacred hot spring site! Their excitement ebbs, however, when they arrive to find it in dire need of repair...

As spring finally arrives, Hakaba's party finally finishes their journey to the coast. As they begin their research on the new region, Hakaba is swept into an underwater cave by its residents--who are indistinguishable from fish! Will Hakaba be able to figure out how to communicate with the inhabitants and escape from the cave before it's too late?