One of the many varieties of brothels in Japan. Image clubs specialize in satisfying fetishes, i.e. the customer pays lots of money for a girl dressed up in a costume that turns him on to perform sexual acts on him (or let him perform such acts on her). Surprisingly, actual vaginal intercourse is usually not offered; most girls won't go further than giving blow jobs.

Anyway, "perform" is the key word, since acting the role is probably the most important thing. The most popular fetishes by far are schoolgirl and nurse; others are various anime characters and uniform-wearing professions.