A young girl chosen by the Holy Sword at a tender age. However, she was separated from her parents by the King's schemes, lured by sweet words from a monarch who wished to monopolize her power. She has lived her life shackled by the weight of responsibility, believing that if she runs away, her parents will hate her, and if she doesn't fight, everyone will be angry. As a result, she is constantly plagued by self-reproach. Under the guise of 'mental training,' she was subjected to constant verbal abuse, which has worn down her spirit and left her with extremely low self-esteem. For the same reason, she was only ever given meager meals, resulting in poor physical development despite being in her growth phase. She was sent on the quest to defeat the Demon Lord with a budget so low it was exhausted after buying a single cheap potion, and was given a strict deadline of one month. Because of this, she ignored all other high-ranking demons and headed straight for the Demon Lord; consequently, all her equipment except for the Holy Sword is cheap junk. She always speaks politely and has a habit of saying, 'Someone like me...'

The Demon Lord's right hand and butler. He treats Ain kindly and immediately reports any trouble to the Demon Lord's ears. He holds command over the other servants and fulfills the Demon Lord's wishes to the best of his ability. He is not a 'yes-man' and will admonish the Demon Lord if he believes they are in the wrong.

One of the maids serving in the Demon Castle. She is a human, just like Ain, who was abandoned in the Demon Lord's territory to reduce the number of mouths to feed and was picked up by the Demon Lord by chance. She serves as Ain's caretaker and friend, looking after her daily needs. She is about the same height as Ain, but her large chest is noticeable even through her maid uniform.