From Twitter today:

Ah, but there’s a twist. Per the full logline, as posted by Deadline:

Set in a beautiful seaside town on the Italian Riviera, the original animated feature is a coming-of-age story about one young boy experiencing an unforgettable summer filled with gelato, pasta and endless scooter rides. Luca shares these adventures with his newfound best friend, but all the fun is threatened by a deeply-held secret: he is a sea monster from another world just below the water’s surface.

The movie is directed by Enrico Casarosa, who previously did the short La Luna.

That promo image is gorgeous.

Luca is set for a June 18, 2021 release.