"There are two types of monsters in this world, Investigator. There are monsters like Ghouls. They're monsters who can survive by being monsters, eating humans in order to live. It's their instinct to live, it's in their nature. They're not inheritly evil, they're only doing what they are born to do: survive. And then... there are monsters like me. Monsters who kill not for survival, nor for pleasure... but to make a point. The only ones who should kill are those prepared to be killed. Now, ask yourself this: which is the real monster? Them... or me?" -Luka Mezame, in his conversation with Koutarou Amon
Luka Mezame (ルカMezame Ruka Mezame) is the protagonist of the story, Tokyo Ghoul: A Flower Colored Darker Than Black and it's spin-off series, Tokyo Ghoul: A Flower Painted Bloody Red.
Originally human, his chance encounter with the Ghoul Rize Kamishiro led him to becoming a half-Ghoul after an accident. For unknown reasons, Lelouch is now inhabiting Luka's body, along with fragments of his memories. Since awakening in his body, Lelouch now lives Luka's life, fooling those close to Luka while all the while coming to adjust in the new world he resides in, while also trying to uncover the mystery of who Luka is, as well as what happened to his family. After joining Anteiku and Helter Skelter, he learns how to coup with his new life as a Ghoul, and quickly became known as the Eyepatch Ghoul. Alternitavely, with his encounter with Investigators Koutarou Amon and Kureo Mado, he introduced himself as Zero.
After escaping Aogiri, and later destroying their base in the 11th Ward, Lelouch comes to see what truly creates the rift between Ghouls and humans, and recalling his own world, decides to bridge it by establishing the Ghoul Organization Yggdrasil, which functions similar to the Black Knights, targeting the corrupted filth of society such as mobsters and gangs and criminal underground rings, as well as Aogiri. He also redons the persona of Zero, the masked revolutionary, and leads Yggdrasil. Due to the unique appearance, and overall overwhelming power of his Kakuja, the CCG gave him the alias Demon King (魔王, Maō).
In the spin-off, Lelouch leaves Anteiku and Helter Skelter, joining Aogiri and assuming the identity of the Eyepatch Ghoul, acting as an Executive Member of the organization. He is typically paired with either Tatara or Ayato, both of which seem to respect him, the former more than the latter at any rate.