|Other names||Devil of Grief|
|Route for history||Asato's|
|Voice actor||Tōru Ōkawa|
|“||You need to bite back. In order to protect yourself.||”|
Unlike the other devils, Kaltz is much slimmer seeming and lacks any visible muscle tone. His hair is a dark transitioning gradient of blues worn in an uneven bob with split-style bangs. Unlike ribika, he has humanoid (though pointed) flesh-tone ears, a pair of long, curving black horns atop his head and a hairless, glossy black tail.
His attire is entirely in mute colors- sheeny black and dark blues, accented by dull brass buckles that decorate the entirety of his outfit. Beneath the cape and jacket he wears heeled boots and form-fitting leggings. More often than not he carries himself somberly with a melancholy bordering on despondent expression on his face.
Kaltz is a very quiet individual who usually speaks with a soft voice and seems to have few things in common with his fellow devils. He even seems to care little for power, and, contrary to his compatriots, carries a detached kind of sympathy for the Ribika—going so far as to apologize for subjecting Konoe to the pain of the emotion he governs. Kaltz prefers to keep to himself and has little love for Verg's crude methods, responding to his taunts and harassment with icy indifference. Though not an inherently violent person, it would be foolish to underestimate him.
Vital fragments of Kaltz' past can be looked into through the second volume of the Lamento -BEYOND THE VOID- drama cds.
Kaltz was originally a ribika—a cat, just like a majority of the character cast. Born into and a part of the Meigi Clan, he had little contact with the outside world. Depressed, he felt very detached from kin, instead choosing to wander away at night.
This is presumably how he met a cat named Kaya. Sadly, Kaya belonged to Meigi's foe clan, Kira. These facts, however, did not hold the two apart, and a forbidden romance held in secrecy blossomed forth. Sadly, what little happiness Kaltz had been blessed with was taken away in what felt like only a short time after finding it. It can be assumed, insulted by his lack of respect and simply bored and looking for something to do, an admired entity to the Meigi planted a seed within each clan to cause strife among their members.
Arranging one final meeting, Kaltz and Kaya conspired to run away together, but was found before they could. It is then revealed that Kaya carried their child, and splitting with the plan to reunite outside of the forest, Kaya was cornered and later captured by her clansmen while Kaltz met his untimely fate at the hands of his own people. After his death, Kaltz was reborn a devil.
- Kaltz and Verg are good with close-ranged attacks unlike the other two devils.
- Verg clearly shows sexual attraction toward Kaltz, however the feeling is not mutual.
- Kaltz is the only devil known to have fathered any children in their prior life.
- Despite being easily seen as the most physically weak devil, his ability to deviate from his nature and role as a devil could be seen as a strength above the others.