Here's what I posted on another board recently when the subject of AGON came up:
MABOROSHI-NO DAIKAIJU AGON (Agon, the Mysterious Giant Monster) was a television mini-series produced in 1964 by Nippon Denwa Eiga, written and produced by Shinichi Sekizawa, who was one of the main scribes for Toho's 1960s fantasy films. It was shot like a feature, but was structured in four chapters (much like some of the Mexican horror-wrestling movies from the 1960s). Legend has it that the original airing was stopped by Toho, who claimed there was infringement on Godzilla, but it eventually aired in 1968. (Apparently, this story is not true, but Toho did show some concern when it was in production -- but they okayed it -- in actuality, the broadcast was delayed because the sponsor dropped out).
AGON (English sales title AGON, THE ATOMIC DRAGON) is a slow-moving, low-key, black and white affair, that is probably best viewed as a curio of the time -- it's production paralleled the Eiji Tsuburaya's own ULTRA Q (produced in 1964 through 1965 and airing in 1966). Ironically, AGON was issued on VHS by Toho Video in the 1980s (and subsequently in 1993) and on DVD in 2005 by King Records. The monster suit, created by ex-Toho employee Fuminori Ohashi (who worked on the original cycle of Toho's monster films), refitted the costume for use in five episodes of THE SPACE GIANTS in 1966.