Some characters in the franchise have or have had very sad fates which they had or have to face. Let's go.

#5 Jacky Heavens

Having downgraded herself from one of the toughest characters to a literal mess with all kinds of issues, Jacky's self-chosen path was the path of isolation and complete hollowness. It's like she is giving herself away to her career and the public and ends up all alone (at least mainly). It's like everybody stopped caring about what happens to her because they know they can't change her mindset amymore. It's like she's a shadow, only existing on stage.

#4 Kaoru Mikami

Before his redemption, Kaoru had to befriend the fate of eternal life and never-ending existence for all eternity, even though this mentally damaged him so much. Kaoru was suffering from it. Imagine to be stuck in depression and there's no way out. Being pulled underwater, trying to swim to the surface just to be crushed by the next wave. Prisoned in the cage that is his mind forever, being lost in the darkness and shackled by fears, anxiety and bound by pain, drowing in tears and dark thoughts. He was forced to live with loss as his mist loyal companion, seeing everyone around him die, watching the world as he knows it change little by little. He can't die, nor can he end this pain by himself or is there any salvation (other than that one curse-breaking song). This would be such a sad fate if he hadn't been redeemed at last.

#3 Zain Kaleo

Zain's fate was was more terrible. He actually disappeared during the aftermath of the Alolan War. Everyone assumes that he was torn away by one of the last Sky Pulses and lost his memories once more, even though he never wanted to forget again. That is really sad.

#2 Ren Arima

Not only is Ren stuck in a child's body forever, the body he is prisoned in is weak, threatening to fail at any moment. He's constantly plagued by weakness attacks that keep coming amd going like visitors. He's destined to reside in a body that, in distant future, might just simply give up and succumb to its weakness- might die. His body has tolerated too much damage already so that it can't take much more.

#1 Charlie O'Brien

Charlie, a member of the Flower Garden Guild, has a genetic disease without any known cure. It's usually manifesting in people around the age of 40, but in rare documented cases, it appears during childhood already. It kinda starts with emotional outbreaks and breakdowns and progresses in the shape of memory and muscle loss, the body steadily weakening with no way to stop it. While wveryone in the guild blooms, he's afflicted with the curse of withering away, knowing that there's no reason for him to fight for his life since he's destined to lose it soon. His fate... is to die, and his life is short, abscent of any joy. It's a curse of darkness and cold...

That's it. These are the saddest fates in the whole series. Did I overlook one? Do you recall one more? Text me in the comments!