I see reviews on Amazon Japan with lower ratings for That's BD-R listings with æµ·å¤–æŒ‡å®šå·¥å ´ç”Ÿç”£ (the text in mariner's image above, maybe equivalent to "overseas factory production"); the user reviews state that the discs are from Taiwan and such, and are made by Ritek. (This information courtesy of Google Translate).
A few of the posts also refer to this maybe being the result of a joint venture with Sony; if that aspect is correct, given the Sony has been known to use Ritek as well, it would make sense.
Given those user reviews, I'm assuming that the actual disc model is a RITEKBR_ code, and not an outsourced Sony or JVC/TY MID. But I would be happy to see that guess be wrong.