She and Kosuke grew up together like childhood friends, having lived in the same house when they were young. Because Kosuke was so clumsy and unreliable, she tended to act like an older sister to him despite being the same age. Their relationship soured for a certain reason, but this incident becomes the catalyst for their reconciliation. She tends to be very conscious of others' opinions due to her family history and personal circumstances.

Hairstyle: A short, neck-revealing bob. She has calm brown hair with bangs naturally falling to eyebrow length. Eyes: She has brownish eyes with a purple tint, and her gaze is kind and clear. Her slightly flushed cheeks give her a cute impression. Physique: She is on the slender side, with long limbs that give her an active, athletic appearance.

A character who embodies the image of a proud, mischievous, and typical immature childhood friend. To put it nicely, he's familiar, but he's so one-dimensional and cliché that there's absolutely nothing new about him. Above all, he refuses to sacrifice his own pride, making the things he says the root of almost all the trouble in the story. However, he shows a kinder side internally, working hard to reassure his friends by acting proactively to solve problems early on, and opening up his true feelings to comfort Natsume midway through.

Hairstyle: Short, dark navy (or black) hair. It has a slightly spiky, natural look. Eyes: He has deep teal eyes with slightly drooping eyelids, giving him a characteristic lethargic or cold look. He keeps his mouth shut tight, projecting a serious atmosphere overall. Physique: Like the female characters, he has a thin and straight build.

Reina's best friend and a 'healing' type character. She's practically the only one who can keep Reina's outbursts in check. Along with Yuzuru, she has a calm personality but shows great decisiveness when words or actions are needed. She is one of the characters who suffers the most in the story.

Glasses: She wears round silver-rimmed glasses, giving her an intellectual and diligent impression. Hairstyle: A bright brown bob that doesn't reach her shoulders. She keeps it neat with a yellow hairpin on the right side. Eyes: She has gentle, round eyes and a quiet, cautious aura. Top: She wears a lime green short-sleeved shirt under dark blue overalls. The white collar of the shirt adds a tidy feel. Bottom: Short-style overalls that are easy to move in, featuring pockets. Shoes & Socks: She wears long light blue socks with black flats, a more subdued style compared to the sneakers worn by the other friends.

A female student from the same school as Kosuke. They aren't in the same class, as she first appears bumping into Natsume in front of the classroom door while leaving school. As the daughter of a wealthy family, it's obvious to everyone that she has a crush on Kosuke. Consequently, she views Natsume as an eyesore and pours out insults whenever she sees her, regardless of the reason.

Hairstyle: Long brown hair tied in a high ponytail. It's accented with a pink ribbon at the crown, and she wears colorful yellow and mint hairpins on the side of her bangs for a bright look. Eyes: Brown eyes with emphasized eyelashes, making her look sharp and capable.

A blunt boy with a faint presence. Before the building began to drift, he only appeared briefly as a silhouette, but after the drift begins and the children fall into a panic, he appears as a jump-scare at opportune moments.

Hairstyle: A bowl cut (bangs) trimmed straight above the eyebrows. His hair is a very deep black, giving a neat impression. Eyes: He has drooping eyes with blue-tinted pupils, giving him a unique, somewhat sleepy or dazed look. Expression: He keeps his mouth in a straight line with an expressionless face, suggesting a quiet personality with little emotional fluctuation. Top: He wears a mint-colored sweater with a yellow and blue argyle pattern on the chest. A white collared shirt is worn underneath, showing very neat and polite attire. Bottom: Very short black shorts. Shoes & Socks: He maintains a soft pastel color palette by matching long lime green socks with clean white slip-ons.

Friend 1 of Kosuke. He is quite introverted and speaks softly, making him a warm person just like his face suggests. He is the one who makes the most rational judgments in the work. He plays the role of mediator when the children get angry at someone or argue with each other.

Top: He wears a red short-sleeved T-shirt with a large white 'V' logo in the center of the chest. Bottom: Loose-fitting navy shorts that reach the knees. Shoes: He wears light blue and blue velcro sneakers, emphasizing functionality and ease of use.

Friend 2 of Kosuke. An energetic and somewhat clueless but pure character. He is the one who begged Kosuke and Yuzuru to go explore the apartment complex, creating the opportunity for the three of them to find Natsume. He has a habit of saying 'two bodies, one mind' instead of 'one body, one mind.'

Hairstyle: Short light brown hair styled with his bangs pushed up. The spiky hair reflects his active and mischievous personality. Eyes: He has light brown eyes with short, thick eyebrows arched upward, giving him a confident and brave impression. Expression: His wide-open mouth and bright smile show his cheerful and uncomplicated nature. Top: He wears a sporty zip-up jersey in a white and lime green color scheme. It appears to be functional clothing with orange zipper accents. Bottom: Black training pants in a jogger style that tapers at the ankles. Shoes: He wears white sneakers with blue and yellow accents. They look like laceless slip-ons or functional running shoes, showing he's ready to run at any moment.