Sinner Jo and boarder guard Akira make an unlikely team—but now their shared suspicion of lord Harujion’s “Mermaid Island Operation” has brought them together for a daring mission! Sneaking into lord Harujion’s residence, they will risk it all to discover the truth of his wicket plans... Ryuu, who has let herself become a pawn in the lord’s scemes; Jo, who leads the rebellion against him; and Yuki, the human who is tossed in the turbulent waters between them... Where will they all lay when this tsunami of a story crashes into its conclusion!?