Eis is the secondary protagonist of The Soft-Hearted Devil, sharing the role with Dante. He is the as of yet unnamed teen who accompanied Dante during the beginning of the story. He too is a Devil Hunter, though more of an apprentice than a full fledged hunter in terms of experience and skill.
Eis is a tall, slender fellow with a tangled mess of white hair and eyes that shift between green and blue. He is rather pale, pasty as he describes himself, and always wears a smile that is a mix of cocky, sly and knowing at the same time. While he lived in Hamaoni, he wore rough attire consisting of torn pants, worn out shoes, long sleeve shirts with visible patching and a grimy beanie to conceal his mess of hair. After the events leading to his departure, Eis donned his father's old attire consisting of a navy blue over coat with a beige belt looping through it, black pants made of a highly flexible, loose fitting, damage resistant material, beige boots with silver clasps and black straps, and a light grey vest made of woven Kevlar and another fabric with the strength of layered titanium and the softness of fine silk over a white shirt of the same material. Within his coats pockets are several Devil Arms, most of which are larger than the outside of the pockets themselves. These arms consist of Septentrione, an energy weapon of various forms and abilities with a base shaped the top of an ornate cane; Maxwell, a two-part quarterstaff with control over the environment and teleportation; Melchsee, a tuning fork shaped sword and short spear set with the ability to manipulate gravity and singularities of greater power as attacks are blocked and countered; Laplace, a combining pair of guns that fire and detonate ricocheting shells of demonic energy while separate and act as a heavy laser cannon when combined; and Lemegeton, a tome and gauntlet set capable of summoning the apparitions of the demons recorded within the tome's pages to assist in battle or synchronize with the user to utilize various unique skills, each a memento from his father for his eighteenth birthday.
Personality wise, Eis is quite the enigma to those who don't understand him well. He always seems to know secrets or what will happen before it does and has a penchant for saying things will happen immediately preceding their occurrence. This is because of his strong ability to detect demons and other supernatural entities as well as similar occurrences, something inherited from his mother's side of the family. In actuality, Eis is snarky and sharp tongued, but not to those he respects or sees as allies. He treats his enemies like playthings, generally toying with them before crushing them to show his strength. He is cocky, but not overconfident without a valid reason, and relies more on wit than brute force when his mean streak isn't showing.
Eis has had little revealed about him in the story so far, but in his upcoming side story and the next chapter of The Soft-Hearted Devil, may be a bit more enlightening about him.
The depths of Eis' relationships have yet to be explored beyond his partnership with Dante as an apprentice of sorts. More to come.