What is the relationship between Souichiro and Aikuro?
Souichiro Kiryuin (鬼龍院 総一郎)
鬼 = Demon
龍 = Dragon
院 = Ex-empress, academy, institution
(Souichiro changed his surname to Kiryuin when marrying Ragyo)
総 = Whole, together (includes kanji for thread)
一 = One
郎 = Son
Aikuro Mikisugi (美木杉 愛九郎)
美 = Beautiful
木杉 = Cedar Tree
愛 = Love
九 = Nine (derived from a pictograph of a dragon)
郎 = Son
You're reading too far into the names. Trigger loved picking over-the-top names filled with puns for Kill la Kill cast. Literal dictionary definitions are pointless to dissect here. Learn Japanese first and come back.
I don't see how pointing out parallel kanji construction in the given names of two characters who look almost exactly the same is reading too far into things.
Assuming that the nine son thing alludes to a Chinese myth might be reading too far into things but no one can say that with certainty at this point.
You claim that Trigger picked names filled with puns. What are the puns here? Why can't the names use allusions? Honnoji Academy was a direct historical allusion. Rinne-Do was a pun that alluded to samsara. What should I be dissecting if not names?
I'm working on the Japanese but I'll note that you have not proved that fluency is a requirement for name speculation.
you like parallel construction? how about this,
If they are related they're probably brothers. Satsuki is sure he's dead and said he himself knew he would be offed by Ragyou. Assuming him being dead is true they can't be the same person.
This could be another red herring like Tsumugu and Kinue were though. 郎 is an incredibly common ending kanji for boys' first names in Japan. It's on the same level as 子 for girls.