Seshio Gwendolin

Seshio is the Cheshire Devil in charge of Japan and the leader of the current generation of Cheshire. He is the first Cheshire Devil introduced, and is in charge of planning all of Cheshire's actions.

Cheshire Devil form
As a Cheshire Devil, Seshio has a large, oval shaped head with a grinning mouthpiece and eyes that resemble targets. There is a small torso with a target ornament atop it attached to the head. Beneath this torso there is an antennae-like attachment that appears to control a floating, striped tail. The end of this tail that seems to function as the receiving end for the energy put out by the antennae also has a target on it. His Devil form is apparently 5m tall.

Seshio's Cheshire Devil avatar has large paws that he uses to transport Alice and World Devils into Wonderland. He is capable of increasing these paws to a size capable of transporting entire cities, and apparently is able to transport World Devils he could not transport on their own by transporting the area around them.

Human form
When not in Cheshire Devil form, Seshio is a short boy with straight black hair and light eyes. He wears a black, long sleeved shirt with a white cross on it, which distinguishes him from the rest of Cheshire. He also wears black shorts and boots. He has a circlet with the symbol of Cheshire on the right side. Despite being a year older than the anomalies, he is very small compared to them, and they remark that he is only a kid.

Personality
Seshio places the value of Wonderland and Cheshire above all else. He is in charge of all plans to stop Maze's invasion, and also takes command of the efforts to save the Cheshires that have already been arrested. Being chosen as the future leader of Cheshire from a young age, his duty to Wonderland had been hammered into him for years. As a result, he shows the most loyalty to the world of Wonderland itself out of all Cheshires, putting Wonderland above his brethren, and dies in an attempt to prevent it from collapsing from Shinonome Azuma's mock anti-proton bomb.

He is extremely abusive towards Lukyon, beating, stabbing and burning her for misbehavior. He also attempted to whip her with an electric whip at least once, only being stopped by Kuroe. He claims that punishing her is his duty. To a lesser extent, he is also verbally abusive towards Masoto on many occasions, as well as slapping them once. He is rude to Scapp, calling him a traitor and often making fun of him for laziness, but it seems to be presented in a significantly less serious manner - Scapp is indeed very lazy and laughs it off, and Seshio never hits him. The reason for Seshio's cruel behavior towards his brethren is never explained, but it is possible that it was drilled into him that he must mind the other Cheshires by hitting them. Alternatively, he could just have a nasty personality.

He is generally not very kind to Alice, shown especially when he berated Kuroe and told her to show some self respect after publicly humiliating her, as well as having no issue with killing Seki Hijiri in front of Azuma if the situation calls for it. Like Shizu, he seems to view Alice as a tactic rather than people. Despite this, he is willing to get down on hands and knees and beg the anomalies to save his brethren from execution.

He used to be very close to both Sallo and Scapp, growing up with them under Cheshire's care. Sallo later left Cheshire due to the deaths the group was responsible for, but the two remained close up until the first night. Sallo met with Seshio often and kept Cheshire's planned terrorist attacks a secret out of affection for Seshio. They were one of the first to enter Zera as a World Devil, and ended up being the first to fight the Alices of Japan. Seshio, being in charge of transfer, seems to have intentionally chosen to fight Sallo, in accordance with Sallo's own wishes.

Trivia

 * His name is sometimes romanized as Secio. This romanization reflects the effect of the name in the original translation - it is not a Japanese name, and is supposed to seem as foreign and strange as "Scapp".
 * In a flashback, Seshio is shown with a doll that looks like his Cheshire Devil form. This could imply that he has already been to Wonderland at this point, or that his Cheshire Devil form was assigned to him from a very young age. Seshio and Giger are the only devils shown holding dolls resembling parts or the whole of their devil forms as children. This could be attributed to the fact that they are the "elite" of their respective groups, and their devil forms are "special".
 * He is formally in charge of writing all descriptions of World and Cheshire Devils due to being "responsible", but some descriptions are written by Scapp and possibly Lukyon as well.
 * Seshio and Scapp are both given the same last name, but all Cheshires are orphans, and the two do not appear to be blood related. This implies that Gwendolin is an adoptive last name for Cheshire.