Pink salons skirt laws against prostitution by serving food, operating without showers or private rooms, and limiting the services provided to fellatio.  There may also be additional activities such as fingering the "companion" and sumata.
Pinsaros exist all over Japan. Women who work in them may service a dozen or more men per shift. 
Allison, Anne (1994). Nightwork: sexuality, pleasure, and corporate masculinity in a Tokyo hostess club. University of Chicago Press. pp. 131–132. ISBN0-226-01487-8.
Hill, Jane H.; Mistry, P. J.; Campbell, Lyle, eds. (1998). The Life of language: papers in linguistics in honor of William Bright. Trends in linguistics: Studies and monographs 108. Walter de Gruyter. p. 127. ISBN3-11-015633-4.
Kempadoo, Kamala; Doezema, Jo, eds. (1998). Global sex workers: rights, resistance, and redefinition. Routledge. pp. 178–179. ISBN0-415-91828-6.