>>235111
>>235112
https://www.sanspo.com/article/20180106-HSWK6JE2F5OXFFJLLJXPJV36QY/
Here's an article stating that Kagamiyama & Kasugano, in their role as NSK PR men, personally warned Takanohana's rikishi (Takakeisho, Takagenji etc) specifically for wearing casual clothing in public. If there weren't a rule written down somewhere, they wouldn't have been able to do that.