In a world full of brilliant heroes, it’s the trust of fans that turns heroes into superheroes. If a hero loses the people’s trust, they lose their special abilities. Trust value is collected, quantified, and used to determine a hero’s ranking, displayed on their wrist. Every two years, the top heroes go to a tournament to fight, determine new trust values, and earn their rankings.

In a futuristic world where humans and mermaids coexist, the life of mild-mannered office worker Stephan is upended when he is suddenly proposed to by Chao — a princess from the mermaid kingdom. With no time to make sense of what's happening, Stephan soon finds himself living with the unpredictable, wholehearted Chao, and her sincere love begins to break down his emotional barriers.