This might be a stupid question, so sorry in advance. In some sumo names like Tochinoshin 栃ノ心, the の seems to be written in katakana? Why is that? IIRC 乃 is used as like an archaic/historical writing of の in names like Asanoyama 朝乃山, but the katakana confused me.
Using hiragana for okurigana and whatnot is a relatively recent development. Katakana used to be used for that.
There is an interesting but too-short thread already: