Our first yojijyukugo was from Takayasu’s Ozeki promotion. Going backwards chronologically, the previous promotion was Kisenosato and he used the idiom futou fukutsu (不撓不屈). This means “unyielding, unbending.” 不 (fu-)is a fairly common kanji, used to negate what follows it. So this saying is fairly straight-forward. Literally, Not deflected, not bent. This was also the idiom used by the great Takanohana when he was promoted to Ozeki.
So, what happened to Goeido and Terunofuji?
Great question! They didn’t do it. They opted for a simple ceremony.
Not strictly on topic but as this relates to kanji… Who decides how the kanji in the wrestlers’ names are pronounced? Could Shohozan just decide that 松鳳山 should be pronounced Matsuotoriyama next basho?