The War of the Gargantuas

A giant, cannibalistic humanoid's rampage through Tokyo is halted by his more docile twin, but neither their reunion nor their scientist caretakers can prevent their eventual duel.

The War of the Gargantuas is a 1970 horror sci-fi movie directed by Ishirô Honda, starring Russ Tamblyn, Kumi Mizuno, Nobuo Nakamura. It holds an IMDb rating of 6.1/10 from 4,085 votes and runs 1h 32m.