Oculus

Oculus is described as the creator of the arbitration system itself, watching over every floor of the tower from a position above even Nona. He looks like a mischievous old man, spending his free time at billiards and growing visibly annoyed if anyone but Nona is offered as a partner.

That playful surface hides a near-nihilistic worldview: he believes empathy and meaning only matter to beings capable of dying, and that arbiters who feel too much are unfit to judge humans at all. His pink hair and beard, styled like a blooming and a closed lotus flower, extend into an ability to read others' memories directly.

When he grows suspicious that Nona is hiding something, he reads the memories of arbiter Clavis and confronts her outright rather than letting the matter drop, refusing to accept her attempts to dismiss him. His disapproval of an arbiter carrying human emotions puts him on a collision course with the very experiment Nona has spent the series protecting.