Children of the Sea
海獣の子供 (original)
Ruka spends her summer at the aquarium, where she’s drawn into an enigmatic aquatic event alongside two mysterious boys raised in the ocean.
Starring Mana Ashida, Hiiro Ishibashi, Seishuu Uragami, Win Morisaki, Goro Inagaki, Yu Aoi, Tōru Watanabe, Min Tanaka, Sumiko Fuji
It's a animation and action & adventure movie, and has a rating of 6.5 out of 10 from Imdb which is usually fine for this kind of movie.
Watch it here
Not found streaming from India.