Champagne, chandeliers and glitzy cocktail frocks are all part of the fantasy world conjured up by Japan’s hostess clubs. The coronavirus has delivered an unwelcome dose of reality.

Men can pay thousands of dollars for a couple of hours’ flirtation, with female escorts sitting close and entertaining them. Even as the role of women has changed in Japan, such establishments have endured in the culture. Hostesses — typically young — are often treated as "cast members” of these clubs under a professional name, and clients don’t tend to want it known that they’ve spent time there.

An infection cluster connected with Club Charme in the city of Gifu in March confirmed what many had worried about — that hostess bars are not only an infection risk but pose special difficulties to the contact tracing needed to stamp them out. Figuring out who visited such clubs, and when and what they did there, isn’t easy.