User blog comment:Xilinoc/Ch. 611 - The Soul King Dies (edgy as ever, Kubo)/@comment-2211792-20141226141529/@comment-24384892-20141226183506

We're also probably never going to know what NaNaNa and BG9's letters stand for.

Kubo either killed off or forgotten about BG9. And NaNaNa lost his powers the last time we saw him.