Ryohei Arisu (有栖 良平, Arisu Ryōhei) is the protagonist of Alice in Borderland. His specialty is Diamonds (♦️). He is portrayed by Kento Yamazaki.
In the original world, Arisu was a moody unemployed teenager, constantly in conflict with his family over his reluctance to attend job interviews. His addiction to computer games, however, proves advantageous to him after he and his friends are transported to the Borderlands, where he is able to take a macro view of the deadly games and deduce certain details about their designs in order to find a solution. As demonstrated during his time in the parallel Tokyo, deep down Arisu is a kind and caring individual, whose first instinct is to help people around him rather than betray them to save himself. He shows compassion to friends and foes alike, attempts to understand everyone's reasoning and see through their anger, knowing that there is usually pain hidden behind it.
Arisu is a tall and lanky young man with shaggy black hair and bangs that cover his eyes. He wears various casual clothing in both the original world and in the Borderlands, which usually includes T-shirts, hoodies, board shorts, and jeans. Blue, yellow, and light beige/white are the dominant colors in his style.
Arisu Ryohei's friendship with Chota Segawa and Karube Daikichi is a central and defining element of the early part of the story. The three are shown as very close friends before they are transported to the Borderlands.