I have a personal theory that has several parts, but it revolves around a central point: Klonoa is Claire.
We're told in Lunatea's Veil that Claire was a goddess who vanished from the world after fulfilling her duty, and that the Ring is a holy artifact that relates to her... And yet it's something that Klonoa seems to have always had and can wield effortlessly.
Now go back to DtP, where Klonoa was summoned to the world by Huepow and had a set of false memories given to him. However, if Klonoa isn't native to Phantomile, then why does he have the appearance of one of that world's races? Well, since dreams come from memories and thoughts, it stands to reason that changing those memories could alter the form of the dream being. Plus Huepow is able to alter his own form at will, so he may be able to change others as well. And who better to bring in to save a world than a divine being?