ultra late t/n: i saw the "zazen girls" poster in chapter 5 and it dawned on me how painfully obvious that "zazen bouzu" was a play on the band zazen boys which i didn't even know existed until i looked it up just now but it was like how could it possibly conceivably not be that ahahaha
or rather, ZAZEN BOYS (their name is officially spelled in romaji) was probably a pun on 座禅坊主 in the first place -- 座禅 means "seated zen buddhist meditation", and 坊主 means "buddhist monk" but is also phonetically similar to ボーイズ and used as a familiar or dismissive way to refer to a boy. it came full circle lmao. also they formed after number girl broke up so there may accidentally be like 3 different incarnations of mukai shuutoku in the btr universe at the same time lol