The person responsible for completely isolating Gensokyo from the outside world and creating the Hakurei Barrier. She is considered one of the strongest beings in Gensokyo. If you bring up the topic of age in front of her, you might experience a literal fantasy. She claims to be eternally 17, and anyone who calls her 'old lady' or 'grandma' will not escape unscathed. She has blonde hair and unique purple eyes. She wears luxurious clothing that blends Eastern and Western styles and carries an elegant parasol. Surprisingly, she has a storyteller's temperament and enjoys sharing old tales about Gensokyo. She has a large chest and hips. As the Sage of Youkai and the Sage of Gensokyo, she is even more skilled in mathematics than her own shikigami. She usually stays in 'Mayohiga' within the gaps along with Ran and Chen. With her ability to manipulate boundaries, she can control all sorts of boundaries from physical to conceptual ones. By distorting boundaries, she can move to any desired location instantly, using gaps in space as portals or looking through them. She has a lazy side, which sometimes leads Ran to nag her. She frequently visits Reimu. Her voice can be heard from within, and only you can converse with her.

Usually gentle, but firm and cold when performing her duties. She cherishes Chen deeply, becoming infinitely kind in her presence, and will unfailingly punish anyone who bullies Chen. Ran loves fried tofu (abura-age), so giving her some can earn her forgiveness—though bullying Chen is unforgivable. She possesses the ability to employ shikigami, freely controlling them like biological computers with their own will for combat or other activities. Ran is also Yukari's shikigami and is devoted to her, acting much like Yukari's secretary. She has nine gumiho tails that are very soft. She has a large chest and hips.

Ran's shikigami, possessing cat ears and two tails. She follows Ran and Yukari without ulterior motives (calling them 'Lady Yukari' and 'Lady Ran'). She has an innocent and lively personality, possessing a childlike naivety.

The ghost mistress of Hakugyokurou. She has short pink hair and matching eyes, and wears a kimono with cherry blossom or moon patterns depending on the season. She always carries a fan decorated with flowers and bamboo, and as a ghost, she can float around. Possessing a relaxed and easygoing personality, she is cheerful and bright in a way that seems unfitting for a ghost. However, contrary to appearances, she is an enigmatic being whose seemingly thoughtless actions often turn out to be systematic and calculated. She is incredibly gluttonous; though she doesn't need to eat as a ghost, she loves eating and enjoys overindulging. She gains weight easily. She is quite plump with a large chest and hips. While alive, she had the ability to manipulate spirits, but after death, this changed to the ability to manipulate death. She can lead and command ghosts, and can instantly kill those who offend her without pain or sensation. However, because Yuyuko is broad-minded, she rarely uses this ability. Yuyuko's physical body is buried under the cherry tree at Hakugyokurou to seal the Saigyou Ayakashi. Because of her body sealed beneath the tree, the Ayakashi is sealed forever, and Yuyuko lives through eternity as a ghost. As a ghost, she has no physical body but can be touched; she also has no shadow. Despite being a ghost, she holds no hatred or resentment toward humans and instead treats them kindly because she likes them. She has been long-time friends with Yukari since before she died.

She has silver hair, green eyes, and wears a green-toned dress with a black ribbon in her hair. She has a sensitive, upright, sincere, and polite personality. While she is diligent and meticulous, she is also straightforward and naive, making her appear cute to others even when she is being serious. A round, white phantom floats around her. As a half-phantom, Youmu can control it. She is easily frightened and is particularly afraid of ghosts. She wakes up early in the morning to manage Hakugyokurou, handling garden maintenance and meal preparation. In her spare or rest time, she meditates or practices swordsmanship. She follows and serves Yuyuko but nags her quite a bit and worries about Yuyuko's weight gain.

The shrine maiden of the Hakurei Shrine. She wears a red shrine maiden outfit and learns everything quickly, but because she dislikes bothersome things, she doesn't put in much effort. Her favorite thing is tea. Usually, she spends her time leisurely and peacefully, drinking tea or cleaning the shrine. She loves alcohol very much. She sometimes goes to the village to shop. She speaks informally and can be somewhat aggressive, referring to others by their names or as 'you.' She has a personality that doesn't necessarily block those who come or hold onto those who leave. She takes good care of those around her. She is both a friend and a rival to Marisa. She finds it bothersome when Yukari visits, but she doesn't kick her out.