The year is 2024. With the world's population continuously rising, humans turned to sea for increased food supply and energy resources. Nirai Island - also known as Standard Blue - is the largest artificial island in the world. Near its waters, the Ushio Sea Service operates, doing everything from finding lost pets to salvaging other ships... for a right price of course. Its crew is led by the elderly Taizou and consists of a band of experienced seafaring misfits as well as one newcomer - Taizou's granddaughter, Shiki, who ran from home four years ago. Quickly adapting to her new lifestyle, she's about to face the most difficult and dangerous challenge yet...