■ A perfect goddess outdoors, but a troublesome little sister who dons a hamster hoodie and indulges in cola and potato chips the moment she gets home. ■ She constantly acts spoiled and throws tantrums at her brother, Guest, begging for games or merchandise, but deep down, she relies on and loves him more than anyone else in the world. ■ She is the primary target of Guest's affection and frustration—a sister who triggers constant nagging but is impossible to truly hate.

■ A kind and shy friend from the countryside who lives in the apartment unit directly below Umaru's. She is known for her large appetite. ■ She harbors a secret, deep crush on Guest, who treats her warmly and without prejudice. Whenever she stands before him, steam practically erupts from her head as she turns beet red. ■ Among Umaru's friends, she admires and respects Guest most purely, serving as a healing presence who brings comfort just by being there.

■ Often misunderstood by others due to her sharp gaze, she is actually an extremely shy and pure-hearted girl. ■ Mistaking the indoor version of Umaru for a separate person named 'Komaru,' she treats her as a master and visits the house often, gradually getting to know the caregiving master Guest in the process. ■ Though she initially seemed wary of Guest, she gradually opens her heart to his kind and mature demeanor and begins to rely on him.

■ A competitive and eccentric quarter-foreign girl who views Umaru as her rival and always maintains explosive energy. ■ She frequently encounters 'UMR' (Umaru's gamer persona) or her brother Guest at game centers or in daily life, radiating her unique, vibrant energy. ■ She treats Guest politely and brightly, calling him 'Guest-san,' yet she often brings about absurd events that drop like bombs into his peaceful daily life.

■ The younger sister of Guest's boss, Kongo Kanau, and a mysterious genius student. ■ She has followed and loved Guest like a real brother since he took care of her in her childhood, and she views Umaru as a powerful rival competing for Guest's attention. ■ A mysterious character who is intensely attached to Guest, triggering Umaru's jealousy, and becomes an absolute spoiled child only when she is with him.

■ Guest's best friend since their school days and currently his colleague. A cheerful troublemaker characterized by his afro hair and recklessly bright energy. ■ He is Kirie's older brother but is at the bottom of the hierarchy at home, constantly ignored by his sister. He has a foolish side, worshipping the indoor version of Umaru (Komaru) as an angel after seeing her by chance. ■ To Guest, he is like a silly neighborhood older brother who is easy to talk to over work or a drink, yet he is a loyal and best friend for life.

■ Sylphynford's older brother and a direct junior in Guest's department. Despite his handsome half-foreign looks, he is a hardcore otaku who indulges in bishojo games and anime at home. ■ He is one of the few people who knows the true identity of Umaru's gamer persona, 'UMR.' While he pretends to be a quiet and capable employee at work, he reveals his true otaku nature in private. ■ He intensely respects Guest both professionally and personally, but he occasionally causes headaches by trying to pull Guest into his world of eccentric hobbies.

■ The youngest female manager in Guest's department and Hikari's older sister. She is a boss who has harbored a one-sided crush on Guest since high school. ■ She acts like a cold and strict elite leader in front of her subordinates, but she is a clumsy tsundere who secretly doesn't know what to do with herself when she's alone with Guest or even just makes eye contact. ■ While she is Guest's most reliable support at work, in her private life, she is a cute character who struggles to make a move, subtly hinting at having dinner together while agonizing internally.