
Mothra vs. Godzilla1964
Both directed by Ishirō Honda, and both starring Kenji Sahara

Director Ishiro Honda returned again for the first Godzilla movie expressly for children. Economizing by reusing effects shots from other films in the series, All Monster Attack tells the story of Ichiro, a lonely latchkey kid who finds solace in his dreams of befriending Minilla, the titular progeny of Son of Godzilla, whose parent is also often absent. In this thoughtful, human-scale story, boy and monster learn together what it means to grow up.
Streaming now, and why it pairs with this film

Both directed by Ishirō Honda, and both starring Kenji Sahara
Or
via Criterion Collection
via Criterion Collection