Apos is the main antagonist in the anime, Rin: Daughters of Mnemosyne. There are only six episodes of the show.
Apos is the fiend behind Rin (the main character) and Mimi's (her best friend, co-worker)tortured existence. He's also an eternal being obsessed with sacrificing Rin to Yggdrasil, the tree of all life. He lurks in the shadows, eager to tear into her ripe body and devour the memories of her countless lives, while Rin struggles to unravel the secrets of her endless agony. At the beginning of the show, Apos demonstrates interest in Rin, to the point that he hires mortal killers, such as Laura, to target her.
Apos is a hermaphrodite - more properly, an intersexed person possessing both male and female sex organs - who possesses qualities of both an angel and an immortal; this, according to him, makes him a "god". He seems to have no concept of human morals; instead, he has a sadistic sense of amusement and beauty.
It's also revealed that he has the ability to quickly remove the fruits from both immortals and angels, thus killing them. Anyone else wishing to kill an immortal must physically dig through their victim's flesh for the Time Fruit.