YOU SAID:

there once was a boy who went to sea

INTO JAPANESE

かつて海に行った少年がいました

BACK INTO ENGLISH

There used to be a boy who went to the sea

INTO JAPANESE

海に行った男の子がいた

BACK INTO ENGLISH

There was a boy who went to the sea

INTO JAPANESE

海に行った男の子がいました

BACK INTO ENGLISH

There was a boy who went to the sea