Tatsuya Tsugawa has just lost both of his parents in a car accident. While trying to live up to his father's dying wish of becoming an upstanding man, Tatsuya rushes to help Seine--his bizarre classmate--from bullies. Little does he know he is about to find himself in the middle of a supernatural war between the immortal Seine and sea creatures that can control humans. So much for being Mr. Nice Guy! -- VIZ Media