35 years before starring in our recently featured film, Orochi the Eight Headed Dragon appeared in another Toho fantasy film, meaning that Eiji Tsuburaya presumably did the special effects.
This looks like one of the '70s TV music numbers where they keep superimposing different views of the singer on top of one another. Either that, or it's a training montage from a demon version of Rocky, with the large face being the hectoring Burgess Meredith figure.