By 
McDonald’s in Japan is collaborating with Nijisanji for an upcoming promotion, though it’s unclear as of yet what it will entail. The Nijisanji Vtubers who will be part of it as Belmond Banderas, Kanae, and Fuwa Minato. They are not sporting new designs for the collaboration as of the time of writing.
Based on past collaborations that McDonald’s Japan announced, it’s possible that there will be new food items on the menu based on the three Vtubers. While McDonald’s collaborations in the west might mean Happy Meal toys, Nijisanji is not marketed specifically for children. So this is the more likely possibility. We might also get to see Kanae, Fuwa, and Banderas in McDonald’s uniforms when the promotion starts.
In the past, when McDonald’s in Japan held a collaboration with One Piece, it was to market a specific type of burger. It also released a promotional video based on the One Piece opening, and you could also get a special One Piece float for a limited time.
Kanae, Fuwa, and Banderas are three popular Vtubers with the Japanese branch of Nijisanji. Kanae currently has 1.17 million subscribers, Fuwa has 827k subscribers, and Banderas has 445k subscribers. All three of them are previously from different groups but mostly produce similar content (gaming streams and song covers).
The McDonald’s and Nijisanji collaboration in Japan will start some time in the future. More details will appear then.
