While following Kurofune, Bocca and Sayako encounter a dead end, but finds 'Nezumikoukoku', or 'Pyramid Scheme Valley', and also find a dam with a mural of a tear on it.
The duo goes to it, and find a beautiful boy with sky blue hair. They also meet up with the artist of the mural, Eichi Hikoyama, who seems to be hired by a woman named Miri Kanaya who owns the dam. Miri also owns mice that gather tears around the world for her dam. Bocca and Sayako pass as art students for Eichi, and stay in the village. The two find out from Eichi that the boy from the dam was neither Monster nor human, and people call him a demon, and despise him.
The next day, Sayako found a girl with a large jewel around her neck, and decided to try and steal it. Meanwhile, another robot creature appears in the valley, of which Bocca quickly drives away. While he tries to chase it, he encounters a whole bunch of mice, who attack him. With an odd sound, he realized he was saved by the girl Sayako met. When she saw he was a Melos Warrior, she quickly drew her bow, and pointed an arrow at him. Exactly what's up with this place?
「鼠講谷」にやって来るボッカと小夜子は巨大なダムに腕を挟まれている”謎の少年”とダムの壁面に絵を描き続ける”彦山絵師”に出会う
絵師の世話になる事になったボッカたちは、谷の有力者”金谷みり”に挨拶に赴くのだが・・・
