Young women standing idly around a park in Tokyo's west suggest that a giant statue of Godzilla is not the only attraction for a record number of foreign tourists.

Their faces lit by the cold glow of their phones, the women lining Okubo Park are evidence that sex tourism has developed as a dark flip side to the bustling Kabukicho nightlife district.

There is no official data, but anecdotal evidence suggests that an increasing number of foreign men are flocking to the area after seeing videos on social media.