I wonder what exactly NPK is.

Artist desc:
The moisture in your Life
"Nippon Pantsu Kyoukai" -> "Japans Underpants Organization"

somewhere along those lines.

Doesnt look like she wearing underpants to me lol

"When you sit, I stand up?" I take it that this is a euphemism?

あなたのくらしにうるおいを -日本パンツ協会-
Bringing flavor to your life - Japan Underpants Association

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