Things in Japan maybe a little different. The office lady seems to perform the same function as the architect/contractor does for Toto toilets.

From one of Patio11's old comments on the Japanese toilet industry:

Toto's primary sales channel is "If you build a house or office in Japan and don't specifically talk to your architect/contractor about your post-bowel movement preferences we will take the liberty of using the most current model Toto has available and then invoice you cost plus labor plus 50%." Toto does not have that relationship with the person responsible for picking your toilet. Why does Toto have that relationship with the guy who picked my toilet? They've got a sales rep in Ogaki. His most important job is making sure they know of every business start for a construction company and that every time it happens the company gets a wreath (that's considered auspicious and is socially mandatory to buy when someone close to you starts a shop) and the principals get invited out drinking. Toto is, naturally, buying. The sales guy will not be so gauche as to mention "Say, apropos of nothing, do you do cost-plus projects? We have a proposition for you which will put $100 extra in your pocket for every bathroom you build."

https://news.ycombinator.com/item?id=4784877

You may find that Japanese salarymen are not scandalized by the notion of a token gift to secure favorable treatment in a business relationship.

They appear to be targeting roughly $20 compensation for a referral ( http://nestle.jp/amb/mgm/ ), which strikes me as well within acceptable bounds here. (And, for that matter, the US.)