Spin-off that takes place 8 years after the events in Full Ahead! Coco.
The Gekido is a giant steam pillar that divides the ocean into two regions. Eight years ago, the darkness that consumes the other side leaked into this side leaving the ocean pitch black. The only people that go out to sea now are fools and pirates. A young man named Cherry Blossom has a dream to travel the ocean and goes on a journey with a boy named Son who somehow is in possession of the Teardrop of the Gekido, a mysterious item which is said to hold the key for traveling the dark sea.