Mermaid princess Lucia Nanami has survived several villainous attacks that also threaten her fellow princesses, her relationship with her beloved, Kaito, and the health of the seven seas. When the evil Gackto kidnaps the boy Lucia loves, she has no choice but to gather a rescue party and head to the deepest part of the ocean to confront her enemy. Defeating Gackto requires the magic power of all seven princesses, but Lucia has found only four. This volume is the thrilling climax to the first arc of Pichi Pichi Pitch and features love, adventure, and the revelation of a secret identity.