The Mysterians

The Mysterians, released in Japan as Chiky Beigun ? , lit. Earth Defense Force , is a 1957 Science fiction Tokusatsu film directed by Ishir Honda and produced amp released by Toho Studios. It is notable for being the first Tokusatsu filmed in TohoScope and the first Toho film to use Perspecta stereophonic sound. Allmovie praises the film for its excellent special effects.

The films starts with Astrophysicist Ryoichi Shiraishi, his fiancee Hiroko, his sister Etsuko, and his friend Joji Atsumi witnessing a festival at a local village near Mount Fuji. Shiraishi then tells Atsumi that he has broken off his engagement with Hiroko but gives no reason other than an undisclosed obligation to remain in the village. A mysterious forest fire is then seen near them. Shiraishi rushes out to investigate and disappears during the confusion.The next day, Atsumi is at the local observatory, where he meets the head astronomer, Tanjiro Adachi. He hands the doctor a report written by Shiraishi. The report concerns a newly discovered asteroid that Shiraishi theorized was once a planet between Mars and Jupiter. He has named it Mysteroid. However, Adachi does not believe in his radical theory and also points out that the report is not complete. ........

Source: Wikipedia