It's sea! Set sail! Smile, Pun (1990)

A feature-length animation of about 70 minutes of the popular work "Niko Niko, Pun", which began broadcasting in the 1980s as a corner of NHK's educational program "Okaasan to Issho". The original "Niko Niko, Pun" was a live-action puppet show in costume, but in this anime version, the three main characters are voiced by the same voice actors, including Kaneta Kimotsuki. This is Smiley Island, a planet very similar to Earth, located beyond the universe. One day, a letter from his mother arrives at Porori, a mouse boy .

Unfortunately the movie It's sea! Set sail! Smile, Pun is not yet available on HBO Max.