E-rated game, with the cutest protagonist ever taking up the cover. Naturally, it's going to have the happiest ending ever, right? Hoo boy, are you wrong.
All throughout the game, Klonoa is forced to undergo all kinds of psychological abuse, mostly comical (tending to be met hostily by others when he first meets them), to downright depressing (having his own Grandpa die in his arms). All throughout the game, you just want to see things work out. Prepare for the disappointment of a lifetime.
At the resolution of the game, Klonoa was forced to risk Huepow's life in order to defeat the Big Bad Nahatomb for good, after three long phases of battle. Meaning he was forced to lose yet another person closest to him, right?
Actually, no. Huepow reforms himself behind Klonoa as he begins to mourn, though he's greatly weakened by the battle. He makes it out okay, though rather tired from the blast.
End-game, Klonoa and Huepow are relaxing peacefully on the hills of the Wind Village, talking about how their friendship is going to work now that he knows Huepow is the Prince of the Moon Kingdom.
... Well, actually, Klonoa's the only one doing it. Huepow's not saying a word. Klonoa dismisses it as the worst-case scenario for all of his questions being the actual answer, but manages to accept all of it, just happy to believe they can still play together at all. He relaxes, understanding Huepow's position, and just being glad they'll be friends, expecting a never-ending friendship.
... And then Huepow drops the truth.
"You aren't... You don't... You don't really belong in this world!"
This revelation gets Klonoa's attention quickly, as he waits for Huepow to just pass it off as a joke, or even a cruel lie, as he's begging Huepow to just stop talking. But he keeps going on, revealing to Klonoa that he was pulled out of his original universe, and all of the memories he had in Phantomile were faked. And, as the biggest slap in the face, when Lephise sings her Song of Restoration to reform the land to it's blissful state before it was attacked by Ghadius' malice, he would be taken out of the world, no choice about it, because he himself was an unnatural tick mark that didn't belong. Huepow tries to explain that it hurts him, too, but then it happens: Lephise's Song of Restoration begins to play. It apparently plays all throughout the kingdom, Klonia and Huepow hearing it easily. As the song goes on, a large portal opens up in the sky, and Klonoa feels it begin to pull him. Huepow says it's time to go; that Klonoa needs to go back home, to HIS Phantomile. But the whole time, Klonoa's struggling to hold himself on the ground, to reach his friend to hold him down, exclaiming in utter terror that he doesn't want to leave. Huepow, in tears, loses his composure, running out to try and anchor Klonoa down himself, just before he can fly off, as they both cling desperately to the Wind Ring. The scene hurts so badly, watching both of them flail about with screams and struggles and full-on sobbing, just trying to keep him in, before Huepow unfortunately loses his grip, sending Klonoa soaring off into the portal. And the real kick in the shin? It's not until AFTER Klonoa's gone that the kingdom starts to truly be restored. The grass turns green, the windmills turn, and all that had been lost in the story began to heal. It ends on the note of Huepow wiping his eyes, before gently smiling at the sight of the world healing around him.
What makes this ending so great is various factors. For starters, this is something that could have been picked up on at any point in the game. Every level is referred to as a "vision", Ghadius mentions a "strange dream" as he's bringing Nahatomb to life, even Nahatomb itself is revealed to be specifically out for Klonoa's blood. Yet it was still hidden just well enough that it was hard to really figure it out. And even then you expect a happy ending. The next reason? This is THE most painful payoff to come out of everything. Klonoa didn't even WANT the quest before he was forced to go through it, yet he still gave his best effort to saving the land he thought was home. And his reward? THIS. It's painful to imagine that all of Klonoa's hard work was just building up to him being painfully ripped away from the life he thought he had, especially in a game so cutesie in innocent. But what really makes it hit home: Klonoa's still just a child. A young, innocent, fun-loving child. All Klonoa wanted to do was stop Ghadius and be able to live his peaceful life of playing with Huepow and sitting in Grandpa's lap and just being happy. In many other scenarios where similar situations have happened, because the characters were older, they were more easily capable of letting go. It would hurt, but the truth they know to be true would be enough to let them let go. But Klonoa was so scared; so frightened; so betrayed and so hurt; he didn't want to go. He struggled until the very end to fight the truth and stay in the life he loved. And given the utter hell his adventure put him through, and the situations he was put into that no child should be put through, he deserved that much.
It was easily one of the most heart-wrenching ending to any video-game I've ever seen (and in a PLATFORMER, no less), and it remains one of my all-time favorites.