DXD: Adventures into the Known and Unknown

Just like with any other DXD story, The ORC gets mad at Issei who fails to confess, however Ravel defends him much to his joy and relief, then in a crucial moment, Issei loses his temper and snaps and reveals the reason why and storms out. There at the seaside Issei meets a mermaid and forms a friendship with her and gets closer to Ravel, however that's only the tip of the iceberg. 'cause it's gonna get wilder than that!