Whilst fishing off the side of his small sailing boat, Sero sees something in the ocean that he has only ever heard of in stories from fisherman who he thought had been out in the salt spray a little too long. A huge, muscled creature, half fish half man, with deep blue scales and crimson eyes that look straight into his.

When the creature beckons him into the water he pulls his shirt off and jumps, knowing that it’s stupid, but not willing to miss what might be a once in a lifetime opportunity.

Iida Tenya is one of the youngest and most well decorated CEO’s in history. He and his brother specialise in super high performance engines - Tensei designs and manages the building side of things and Tenya handles the day to day CEO work, meeting with high profile clients and signing deals that almost everyone else would call impossible.

He’s top of the 30 under 30 list every year. One of the most eligible men in Japan.

But he’s miserable.

After yet another failed blind date and a few too many glasses of wine he finds himself in an internet wormhole – researching ways to solve his perpetual singleness – and before he really know how or why he’s shirtless in a circle of salt chanting in a language that he’s sure he doesn’t know.

And when he comes back to his senses he’s face to face with a demon.

A really…really…hot demon.

But Tenya has a lot of insecurities to overcome before he can let anyone into his heart (or his bed) and he doesn’t realise that he and Sero are up against the clock to figure things out before disaster strikes them both.