TOKYO, Feb. 8 -- When Mobile Suit Gundam Hathaway: The Sorcery of Nymph Circe hit Japanese cinemas on January 30, audiences expected cutting-edge mecha spectacle - not a blast of late-'80s American rock.

Yet the film's surprise ending theme, Guns N' Roses' 1987 classic Sweet Child o' Mine,has quickly become one of its biggest talking points, sending downloads of the 39-year-old track soaring 12,166 per cent on the iTunes Store in Japan.

According to Rolling Stone Japan, streaming of the song jumped 410 per cent on Spotify within days of the reveal, while the band's debut album Appetite for Destruction climbed to 16th place on the iTunes album chart.

Shazam searches also spiked as cinemagoers tried to confirm that, yes, that really was ...