If you loved Gamera vs. Guiron, try Gamera vs. Jiger
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Noriaki Yuasa, and they both carry the cozy mood tag, and they sit in Action / Adventure / Family / Science Fiction territory. If that's the register that drew you to Gamera vs. Guiron, the second film will land in a comparable space — through a different lens.
cozy
What Gamera vs. Jiger is
A family-friendly monster mash for the discerning giant-turtle fan. Jiger arrives in Japan after some meddling with a Wester Island statue. Gamera takes on this new foe, but ends up needing a submarine extraction performed by two precocious children. Mission accomplished, sort of.

