Riku bears many similarities with Sora. He is tall and lean and has spiky white hair. His eyes are a lavender colour and were described to "look like the abyss itself".
He was usually wearing a dust mask and fur armour to prevent him from coming into contact and inhaling Black ash.
Ever since his home was destroyed and he took over as leader of his colony, he's had a somewhat split personality. When the figurative lock on his [heart] is locked, he appears emotionless, cold, and calculating. When his heart is unlocked, the emotions he bottled up are released (often violently). His endeavors with Shuvi has since lessened his split personality and he appears to be more open around her.
Riku is a master strategist and manipulator, much like Sora. He is capable of duping even the matriarch of the Nilvalen family (known as the strongest and smartest Elf at the time) into giving out valuable information, albeit at the cost of his health. Through his efforts and skillful leadership, the [Ghosts] were able to manipulate all the races into forming alliances with each other and drastically change the tide of the Great War, all while standing in the sidelines.
As a 'human' (as they were yet to be baptized or renamed as 'Imanity' by Tet at that time), his body was weak especially when compared to other those from other clans. like other humans, the elemental bones corrode or eat up his skin and organs when they come in contact.
He, along with the other [Ghosts] had mutilated bodies(burned skin that never healed, amputated limbs, and damaged organs) since they applied elemental bones on themselves to hide their identities from the other clans, as elemental bones 'disrupt' magic, preventing identification through senses or the use of magic.
Despite having the Star Grail in his hand's reach, he started to succumb to his wounds while being caught in the impact, and his remaining arm(his right arm) disappeared as he was reaching for it. Deeming himself unworthy/too weak, he starts to call out to the God of Games, or to anyone who would put an end to the war, eventually, Tet shows up and claims the Star Grail, proclaiming, as Riku disintegrated, that one day, they will play another game.
- His name 'Riku' means earth or land in Japanese, in contrast to Sora's name which means sky.
- It is implied that Riku is the first ever living being on the world of Disboard to create the concept of 'cheating without getting caught'. He is also the one responsible for the allocation of the 16 Race Pieces.
- He was still a virgin until his death at the end of the The Great War, as he said himself.
- It is implied that he played a game with Tet when he was a boy.