Yes, it's the children of the head, but there's no indication that the other children married.
Plus, making Taiyo a relative of the Yozakuras would mean that Taiyo and Mutsumi's relationship is incestuous. So, ew.
One thing that's been bothering me is how Kurogao's evidence said that Taiyo's parents were invited to the Yozakura wedding of the ninth head. But there's no indication that Taiyo's parents were willfully involved in the spy/criminal underworld at all. I'm wondering if it's a case of Early-Installment Weirdness or if the author just retconned it and didn't feel like using that plot point anymore.
So the next major arc of the series begins... with the world's most hardcore game of tag.
This is very much in-tune with the Yozakura Family's penchant for Mundane Made Awesome and absurdist action.
mutter mutter "Oh my god there are so many people looking at me! This is so scary!"
[grabs a gun] "Come and get it."
Despite being the most obvious Hunk of the family, he has a very strong case for being the cutest member of the family.
Actually, he's largely been softening up on Taiyo.
Rather than Make It Look Like an Accident, he's only going to make it a nearly impossible and painful task.
Progress!
But more seriously, it's pretty amazing to compare Kyoichiro's treatment of Taiyo at the beginning compared to now.
Well, maybe.
But he's gone from plotting Taiyo's demise every second of the day to genuinely encouraging him without Backhanded Compliments and entrusting him with secrets (i.e. the retrieval of Shizuku's corpse).
He may prank Taiyo and try to make him miserable, but it's more like being an annoying older sibling than an outright Knight Templar Big Brother.
In today's issue, Shinzo is still going full-throttle, even turning on his Blooming for this test. So much for Nepotism, Shinzo says this is a kindness since Taiyo would die in the real world if he fought anyone on Shinzo's level.
The stock "come at me with the intent to kill" line is a tad cliché, but it works in this scenario.
Though, I can't help but feel that this whole scene feels out of place given the amazingly climactic battle with Tanpopo.
It probably won't be a straight fight. I'd imagine it'd be something like stealth or trickery, since the eldest Yozakura siblings are basically invincible against any non-Yozakura/Blooming user in a straight fight.
Even the current "fight to the death" is a game of tag that ends if Taiyo can so much as grab Shinzo.
Honestly, if the Silver Exam is this tough, I have to wonder what the Gold Exam is like.
Edited by reppuzan on Jul 19th 2021 at 4:08:51 AM
These kinds of tests in battle shonen generally don't require outright beating the examiner, because you're ten thousand years too early for that and that's why they're the examiner in the first place. It's like needing a PhD to get into college.
Having Taiyo go up against his elder siblings for the test is pretty clever, since it means that selling the quirky examiners as total badasses is already accomplished by, you know, the entire manga.
Well, that's part of the reason for the exam. Honor Before Reason will only last you so long in a real fight. Shinzo is simply too good of a spy to handle head-on and Taiyo needs his silver license.
It was frankly insulting that Taiyo thought he could handle Shinzo without exploiting his weaknesses when none of Taiyo's real enemies have any compunctions about exploiting his own. The "come at me with the intent to kill" is Shinzo's way of saying, "You'd better drop this or you'll get worse from spies way crueler than I am."

I thought it was only the children of the head who inherit the powers, hence why we don't see any of Mutsumi's cousins in the manor.