ChaO is an anime film that premiered in summer 2025, produced by Studio 4°C.

About the production: the story comes from an original script, the film runs about 90 minutes and its current status is "finished".

Its main genres are fantasy and romance, with themes such as Mermaid, Female Protagonist, Heterosexual and Marriage.

On AniList, ChaO has an average score of 69%, a good score, and appears on 3,461 users' lists.

In a futuristic world where humans and mermaids coexist, ChaO follows Stephan, a mild-mannered office worker at a shipbuilding company, whose life 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. As her sincere love begins to break down his emotional barriers, an unexpected and touching romance begins to unfold. (Source: GKIDS)

Official synopsis from AniList.