It looks like the 1940s are back, but not in a way you'd expect. Military songs are reportedly becoming fashionable with certain segments of youth.

To get a handle on this trend, I spoke with Masanori Tsujita, an expert on the genre who has been writing about the revival.

"Effective propaganda isn't forceful," says Tsujita, speaking in a noticeably quick tempo. "It sneaks into our subconscious and burns its ideas into our brain."