Akaza is an important character who dies in Demon Slayer. The Upper Moon Rank 3 and one of the strongest Demons of Muzan besides Kokushibo, Akaza has been a notable character in the series, especially for killing Rengoku Kyujiro (Flame Hashira) albeit with a close call in his very first encounter.

The one thing that makes Akaza stand out from other demons is his very past. Known originally as Hakuji, he was forced to witness the loss of everything he held dear, leading to him becoming a demon.

In his fight against Tanjiro and Giyu during the infinity castle arc, Akaza remembers his human memories and willfully wounds himself enough to die, eventually going to hell, but not before meeting Keizo and Kozuki, the ones he vowed to protect.

The Mist Hashira of the Demon Slayer Corps who also happened to be some of the strongest demon slayers, Muichiro was more or less a prodigy, becoming a Hashira at the age of 14 only after just two months of joining the Demon Slayer Corps.

Not only that, but Muichiro had been one of the other breathing technique users to unlock the demon slayer mark, making him even stronger.

However, he is one of the Hashira who dies in Demon Slayer as his death comes at the hands of his own ancestor, Kokushibo, the Upper Moon rank 1. This would be a huge blow for the Demon Slayer Corps as they lost an important asset to their organization.

The older brother of Yoriichi Tsugikuni, the strongest demon slayer ever in existence. Kokushibo was an expert swordsman and the only demon to utilize breathing techniques which would be a rarity otherwise among demons except for Kaigaku, a student of a former Hashira.

Kokushibo was an abnormally strong entity and may as well have slaughtered the entire Demon Corps had it not been for Muichiro’s last stand and the relentless assault by Gyomei, the Stone Hashira.

Kokushibo may have been one of the characters who die in Demon Slayer, but his death had been necessary as he was the ultimate tool of Muzan.

He may seem condescending and haughty in his first appearance, but the serpent Hashira of the Demon Slayer Corps wasn’t to be taken lightly. While not exactly vital against fights with the Upper Moon demons, he was still exceedingly strong and would prove to be an important character later.

However, he, like many others, would face death at the hands of Muzan itself, the king of the demons. And becomes one of the more memorable characters who dies in Demon Slayer.

As a Hashira, Shinobu Kocho was relatively weak compared to the other members of the Hashira, but what made her stand out was her genius intellect. Using poison made from Wisteria extract to take down demons rather than simply utilizing brute force.

She would eventually lose her life to Doma and be consumed, an Upper Rank 2 and one of the most sadistic demons out of the others.

What makes her death exceedingly sad and important is her undying will to exterminate demons, even to the point of consuming the Wisteria extract poison herself in the case of being consumed by Doma in advance, resulting in his death.

While she may have been one of the characters who dies in Demon Slayer, she very well didn’t go alone.