Yes, that internal mechanism is only found on body knocks. Also, I don’t see a push knock anywhere, but the internals are the giveaway.
I agree the absence of Pentel branding is odd, but the printing in photo 6 is also unmistakably Pentel in origin. Here are other auctions for WINDOM pencils:
• https://aucfree.com/items/n442340852
• https://aucfree.com/items/v777342993
• https://aucfree.com/items/h1080090882
As far as I can tell, these are legit pieces. The next step is to find a catalog that mentions them.