It's interesting, of course, who Suk-Ai was. Such a seemingly simple character, but he was presented in a very heartfelt way. I think Ivalai the artist understood, but with Gekiza it's hard; I didn't even understand if he was a person or a sword originally. Among the people, only the black knight/ninja stood out.
It's also unclear at what point in the chronology Erebus appeared, but maybe that will be revealed later.