When the Chronicle visited the shop on Tuesday, the shop-keeper said she had a licence to sell the legal highs.
The shop windows are completely covered and there are two hand-made "sale" signs attached to the exterior. No licence - which is now required by law to sell "legal highs" - was visible.
When pressed, the woman said it was an R18 shop.
There was no sign anywhere that stated R18, though there were two small shelf units with a few adult magazines on them, while in a glass counter were Dr Feelgood, Nirvana and PP psychoactive party pills and other paraphernalia.
One of the retailers in the block told the Chronicle that the R18 branding was a "rudimentary attempt and a front to sell the party pills".
Another local retailer said an adult male and child went into her premises to buy the party pills this week and the child told the man they were in the wrong shop.
"We don't want it here - this is not the area for that kind of shop."
Whanganui District Health Board health protection officer Bruce Butters said he understood police were now looking into the shop's operation.
The Ministry of Health Medsafe group manager Dr Stewart Jessamine said the ministry had not yet started a review of licences to sell the psychoactive drugs.