#yusuke mentioned

[jilted-love]

Kurama being physically vulnerable in his Shuichi form actually has nothing to do with his physique because that body he's using is already demon in nature after he turned 10.

It's all about his youki. His youki, before he lost much of its strength and downgraded from the level of an A class, could be transformed into an armor. It's just like Sensui's which both of them recognized as true even if Sensui's was stronger.

So in the Dark Tournament, Kurama with a much weaker youki was basically fighting naked. His original fighting style with a spiritually conjured ki armor was risky because he relied on its defense to tank out the damage. He was willing to take hits just to plan his strategy but that (very old demon) habit came from when he had better defenses with a stronger demonic energy. His white clothing as youko only failed against Sensui because of their difference in power level with Sensui being S class. Kurama in the the Dark Tournament with his A class ki armor could probably take a hit from Toguro's 100% because Toguro was only Upper B class when Kurama used to be A class.

In post canon, however, it's safe to assume that Kurama surpassed A class already because his awakened youki (after witnessing Yusuke's death and revival) that made him able to shapeshift at will became stronger than before his peak in his previous life. His ki amor could have gotten stronger too. In conclusion, Kurama post canon is gonna be more unhinged and reckless in his suicide strategies. 😅

[jilted-love]

I personally headcanon Hiei to be in his 20s to 50s because it's canon that he neglected looking for Hyouga after he felt more confident and immersed in his own power and in my own interpretation, that's a good chunk of years of delay. Why? Because regardless of canon, I want Hiei to grow in power and reputation in Makai and become great enough that he attracted Mukuro's attention before he even left.

Hiei had a lot of achievements in Makai which he gave up to come looking for Hyouga again. He also got a lot of enemies that could have targeted him while he was weakened and only decades of reputation in Makai earns him all that.

This will also mean that he neglected Yukina before he looked for her, before he knew of her existence, which made Yukina suffer longer in captivity and will give Hiei more guilt and reason not to admit to being her brother. Hiei was too murderous and loved being in power that he let his sister suffer longer when he could have saved her faster if started looking much earlier. He was punishing himself for losing his stone when he accepted the pain of jagan operation but it could also be punishment for the delay it took him before he cared enough to look.

If Hiei comes off as naive, that's because he overestimates his own power and looks down on his opponents which is consistent with him since childhood, since meeting Yusuke and then meeting Kaito. Yukina on the other hand can be naive due to choosing to view people as innocent until proven guilty which is not the way of life around crime in both worlds. Their age can be blamed for that naivety but young age for youkai doesn't mean teenage years because they're not human. Koorime are a long lived race. They could be in their 50s to 90s and still be considered young.