Question about 王 and 玉.

Good day shōgi enthusiast. I am really confused about these pieces: 王将 and 玉将.

I know that 王 is used by the reigning champion, or the higher ranked or senior player while the 玉 is used by the challenger, or the lower ranked or junior player. And it doesn't have anything to do with being the sente or gote since this is determine by the furigoma or piece toss.

However I've seen a lot of kifu where it seems to me like 王 and 玉 are just used randomly. One example is the 78th Meijin match last year between Watanabe-sensei and Toyoshima-sensei.

Both are 9-Dan players though Watanabe-sensei is without a doubt the senior player. And we all know that Toyoshima-sensei is the reigning Meijin from 2019. However, in the first game he has the 玉. And in the 2nd game, Watanabe-sensei has the 玉. So this really got me confused.

I'm wondering, what is really the standard rule for using 王 and 玉? Is there some sort of rule I am missing here? Thank you for answering and God Bless =>

One is used for gote and the other for sente. I switched between universal and kanji and that's what it showed. Both are kings.

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