Kaiketsu Zorori: ZZ no Himitsu

Overview

Film commemorating the 30th anniversary of the Kaiketsu Zorori children's book series. Zorori makes an alarm clock machine to wake up in time for free donuts. But something strange happens when Zorori reminisces about his mother and sheds a tear. They see scenes flash by and the ZZ mark on his costume disappears! Zorori treasures it incredibly as it was added by his mother although he doesn't know its meaning. After crash landing in the street, Zorori, Ishishi, and Noshishi are saved by a fashion design student who they quickly discover is Zororene, Zorori's mother. The alarm clock machine had become a time machine and sent them to the past. She and later Zorondo Ron (Zorori's father), help the trio take back their time machine from the police and a kaijuu.

Source: AniList