- "Don't you dare look down on us that are there still struggling to survive!"
—Ryōhei in Chapter 26
Arisu is shown to have a bluish black/darkish blue/black hair and light neon violet/blue colored eyes. He has a pale colered skin and is seen wearing his high school uniform (a white long sleeved shirt with a red t-shirt inside and a blue colored pants with light soil colored belt with a pale aquamarine sneakers)
A 3rd year high school student with the hidden potential to be one hell of an analyzer, he looks at things from afar and checks every details he can find, he keeps track of everything in the he learns so that he can find a way to put an end to this twisted game. Though he still has a long way to go, he further develops his abilities in Borderland, a place where games and human lives are nothing different.
He is often compared to his younger brother by his father, resulting for his lack of self confidence and pent up frustration. He would often daydream and wish that he and his friends would be able to go far away from reality, from his overly demanding father and stuck up younger brother but even so he's able to enjoy life and forget all of his worries when he's with his two best friends, Chota and Karube, both of which are with him in Borderland.
Every time he loses his sanity to the game, he always thinks of his friends, their sacrifices and his promise to them.
Arisu came from a prestigious family. His father is a superintendent in the education department who would often meddle with Arisu's life and keeps on comparing him to his competent younger brother. When Arisu began practicing guitar due to his well-intended teacher's influence, his father moved him away from Arisu's school in order to cease Arisu's newfound hobby. Arisu's younger brother at most of the time belittled him and showed little respect to his older brother. He placed 10th in a national mock exam and strive to showed off and beat his older brother in both academics and sports.
He became friends with Chota during their first year, when he went to give him a piece of bread and give his thanks for covering up for him when he "unwittingly" threw a rock to the window of their house.
He reunited with a fellow classmate in elementary when he and Chota was taken of their money and beaten up. Karube, since then, became close friends with the two and even though they are minor (age of adulthood in Japan is 20), they would often hung out at his bar and drank.