Also known as: ウルトラ6兄弟VS怪獣軍団
a.k.a. "The 6 Ultra Brothers vs. the Monster Army" in Japan.
A theatrical movie from the Ultra Series, released in 1974 in Thailand, and in 1979 in Japan.
This movie is a international co-production between Tsuburaya Productions and Chaiyo Productions, a company from Thailand.
Nowadays, it is notorious for instigating the court battle between Tsuburaya and Chaiyo, over the international licensing rights for the Ultra Series, specifically, the first six entries, (Ultra Q, Ultraman (1st Series), Ultraseven (Series), Return of Ultraman, Ultraman Ace (Series), and Ultraman Tarou (Series)) of the franchise.