Arnas Ainsworth is the main protagonist in the anime and game series 'Yoru no Nai Kuni', also known as 'Nights of Azure'. As a half-demon knight, Arnas is tasked with protecting humanity from demonic threats in a world where night never ends. Her journey is both an internal and external struggle as she grapples with her humanity and her duty. Throughout the series, Arnas forms a deep bond with her friend Lilysse, which becomes a central focus of her character development. Her role is pivotal, as she balances her personal desires with the responsibilities placed upon her by the mysterious Curia organization.