CherryBlooming

No. Black Mass... It's shit!

Kiyokawa is first name

Yep. I dropped the Alola, after finding Ash attending school. XYZ is the best!

If I remember, it was indeed salamander

the demon shifts into another animal, thus healing all of the previous damage. In a metaphor, he is wearing a shirt, it gets damaged, but he changes the shirt itself to anew.

Maybe you're right. But I thought that Kamanue must be prideful now, as he hasn't joined the Twelve Kizuki and hasn't seen the truths of the world. You know, like a man who suddenly gets superpowers and finds himself able to do anything, thinking he's invincible until someone thrashes him down. Most demons, even the weak ones, have this mentality of looking down on humans, even if they are demon slayers. Of course, Hashira are an exception since they are feared. So, I made Kamanue have that kind of personality, as he's still in that 'invincible mindset' phase. How could he lose to some random demon slayer who isn't even a Hashira? Didn't he aim to become part of the strongest demons—the Twelve Kizuki? So, despite losing his arms and having his regeneration blocked, he was enraged. But he's not an idiot either. He didn’t escape because he didn’t feel the threat of death yet. Even after losing two arms, Kamanue still believed he could eat Kotaro using his Demon Blood Arts. But your point is valid too. He was definitely sweating bullets when Muzan read his thoughts. Maybe, after joining the Twelve Kizuki, he understood his true worth.

Moreover, Kamanue, is the same demon who commented on Muzan in his mind. So, I thought that he must be prideful enough about himself.

Yep, that's correct. But this demon is not a normal one. He is ambitious and prideful of his strength and the fact that his hands are like this because of a demon slayer who isn't even a Hashira hurts his pride. So, he wants to kill Kotaro.

There are more than 800 chapters.

Well, Hamon Hashira name is indeed a bit too weird. Ripple Hashira is a bit good, but I still feel it doesn't suit well. Sun Hashira is a good one as Hamon generates energy same as Sun, but I feel weird using it when Sun Breathing exists but Kotaro doesn't use it. So, naming it is a bit unfair. But still, I feel Sun Hashira fits the criteria most. As for Stand, I am not sure. Kotaro will gain Stand in later chapters because giving him now is too OP, but I am still stumped on deciding the Stand's ability. I hope it is something simple yet practical. If you have some ideas, please give them.