Haku is the central protagonist of Utawarerumono: The False Faces, a man who begins his journey with no memory of his past. He is found in the snowy wilderness, barefoot and wearing only a thin hospital gown, by a young woman named Kuon. Suffering from complete amnesia, he cannot recall his own name, so Kuon gives him the name Haku, which is derived from a legendary figure from her homeland who also awoke without memories.

One of Haku's most defining characteristics is his profound laziness. He has a strong dislike for physical labor and often tries to find the easiest way out of any task, frequently being scolded by Kuon for his lack of motivation. He is a slacker at heart, preferring to rest or drink with friends rather than work. This initial impression, however, is a mask for a much sharper and more capable individual. Despite his physical weakness in a world where most inhabitants possess animal-like superhuman abilities, Haku possesses a remarkably quick wit, high intelligence, and excellent leadership skills. He uses his intellect to compensate for his lack of physical strength, making him a natural strategist. Beneath his cynical and snarky exterior, Haku is also soft-hearted and kind. He often complains but is always willing to support and protect those close to him when truly needed.

Haku's primary motivation shifts as the story progresses. Initially, he is simply trying to find a comfortable place for himself in this strange new world, relying on Kuon as his guardian. As he is drawn into the politics and conflicts of the powerful nation of Yamato, his role becomes more significant. He is employed to lead a team that takes care of tasks around the capital, and his intelligence catches the attention of the Imperial Guard, Ukon. A major turning point occurs when he is forced to take on the identity and heavy responsibility of a fallen comrade, which erases his own name and forces him to mature rapidly, trading his lazy demeanor for a resolute and professional one.

His most important relationship is with Kuon, who acts as his guide and protector. They consider each other as family, with Kuon often acting as a slave driver to push the slothful Haku toward independence. He also develops a strong bond with Ukon, a high-ranking official who finds Haku reliable and interesting, employing him in secret missions and affectionately calling him an-chan.

Haku undergoes a profound personal transformation. He begins as an amnesiac, lazy drifter largely unconcerned about his missing past. However, after experiencing a devastating personal loss, he is forced to abandon his old identity entirely. He adopts the name and mask of his fallen friend, becoming a diligent, level-headed, and charismatic leader. This change is not just a superficial disguise; he must maintain the act under immense pressure, suppressing his own grief and self-loathing while leading a rebellion. In this new role, his unbreakable determination comes to the forefront, as he repeatedly pushes his physical body to its limits to protect others, a stark contrast to his earlier aversion to any form of work.

In terms of abilities, Haku is notably weak physically and struggles with tasks that require strength or stamina. His strengths lie entirely in his mind. He is an excellent problem-solver and a master strategist, able to devise complex battle plans. While he is not a fighter, he uses a metal tessen (iron fan) as a weapon for self-defense. Later in his journey, he gains access to an Akuruka, a powerful artifact that grants him superhuman abilities. By drawing on its power, he can fight on equal terms with the world's mightiest warriors, even at great physical cost to himself.