
Quite the Jerkass and Deadpan Snarker at first, as well as highly cynical, but eventually softens later on. A Spiriter, Kalas hails from Mira and is hell-bent on getting even with Giacomo for killing his grandfather and little brother. Kalas is a youth who wakes up in the clinic of Cebalrai, the Farming Hamlet, under the care of a kindly old doctor named Larikush, having been found by a Greythorne named Meemai in Moonguile Forest, unconscious. In Origins, the non-standard game over (you to Sagi)

What you say doesn’t affect the plot (except for one particular instance in Origins, where choosing the wrong answer gives you a Nonstandard Game Over), but giving the right answers will help you fight better, powering up your Spirit Attacks in Eternal Wings and improving the chances of you getting useful cards in Origins.

Though we're not too sure on the knowledge part (as the Guardian Spirit is also like a second, sentient conscience), they definitely endow their Spiriter with powerful magic spells when called upon, and all Spiriters seen so far have indeed had a role in the world's future.

As revealed in Origins, Spiriters are said to be The Chosen Ones, said to wield great power and knowledge, destined to sway the fate of the world. Anyone who is able to make contact with one and allow it into their heart becomes bonded to it, and from then on is now a Spiriter. Guardian Spirits are beings from another world that occasionally drift to the world of Baten Kaitos through Nekton, the Shrine of Spirits in Mira. The unseen avatar of the player, ostensibly the player him/herself watching and being spoken to from another dimension.
