The Invincible Shovel manga volume 5 features story by Yasohachi Tsuchise and art by Renji Fukuhara.

Beyond the safe shores of the Lactia Republic, in the middle of the perilous ocean, echoes a voice only Lady Lucrezia can hear. The voice belongs to Elias, a mermaid of Lernia Hydra, who leads Alan and his companions deep into the sacred waters to seek out the Green Orb…and a message from Lucrezia’s dead father!