Kaiju Fever: Rodan (1956)

Toho's first colour kaiju film directed by Ishiro Honda and featuring the first film appearance of the Kaiju Rodan, who would go on to appear in the Godzilla series. It also features giant bug things called Meganulon which are kind of creepy.
The film actually has quite a dark tone to begin and plays out like a horror before shifting into more usual kaiju territory. It has the standard plot conventions of 'mysterious things being investigated and uncovered' and 'trying to find ways to stop the monster', but it's all very solidly made with some pretty good monster action and ending that somewhat makes us sympathetic towards the Rodans (there are actually two in this film ). Overall very good stuff. ***1/2