The XXX store is unlocked through the Information dealer, and, deals with Sex Toys

You can buy lubricant, a dildo, an onahole, a riding crop and a tickler.  There are also Strap-ons, but, currently only AI players can purchase them.

After level 5, The option Learn to be Submissive will be shown at the XXX store, allowing you to take on submissive training.