The Manster— also released as Soto no Satsujinki (The Two-Headed Killer) — stands as one of the most delightfully bizarre entries in mid-century creature-feature history.
Foreign correspondent Larry Stanford (Peter Dyneley) is nearing the end of his assignment in Tokyo, eager to return home to his increasingly impatient wife, Linda (Jane Hylton). His final assignment takes him to the remote mountain laboratory of Dr. Robert Suzuki (Tetsu Nakamura), a scientist obsessed with unlocking evolutionary mutations.
Assisted by his seductive associate Tara (Terri Zimmern), Suzuki drugs Larry’s drink with an experimental chemical solution. As the mutation takes hold, Larry experiences personality shifts, diving into Tokyo’s nightlife, drinking heavily and neglecting his marriage. Soon, physical symptoms emerge: severe shoulder pains give way to a bulging, grotesque eye, which quickly sprouts into a fully formed second head. Driven mad by the evil entity controlling half his body, Larry embarks on a murder spree, eventually hurling victims—and Dr. Suzuki—into the boiling hot springs of Mount Fuji. In the climax, the monstrous half physically separates from Larry, forcing him into a literal fight to the death with his own evil self on the fiery rim of the volcano.
Filmed on location in Japan under the working title The Split Foot, the production brought together American lead actors, an international co-director pair and an all-Japanese supporting cast and crew, making it a pioneer in trans-Pacific horror co-productions.
You can watch this on Tubi.
