Manster is a favorite among campy horror aficionados and for good reason as it is both unintentionally funny and genuinely creepy. A "Manster" is half-man, half-monster. To accommodate this set-up, the title character has two heads. Back in his single-domed days, the Manster was an American reporter (Peter Dyneley) assigned to interview a Tokyo-based scientist (Satoshi Nakamura). Alas, the scientist was off his rocker, and while experimenting with mutations, he turned the reporter into a double-header. Wait till you see the climax, with the hero battling himself on the edge of a live volcano. Though filmed in Japan, The Manster was based on a script by British producer George Breakston, and acted (if that is the word) entirely in English.
by Hal Erickson synopsis