Haruo

Haruo wears a dark gakuran-style school uniform, with a high-collared jacket and buttons down the front, accompanied by long pants and a light-colored shirt, with a dark, round school hat with a short visor, which matches his gakuran-style uniform.

And the kimono she wears every night on the bridge:

Haruo wears a flowing, long-sleeved traditional kimono decorated with stylized pine trees, branches, and clouds. He pairs it with a light-colored undergarment (his uniform), a wide, dark obi, and zōri sandals, creating a traditional and elegant ensemble.

• Haruo is adopted, as his father feels guilty, but his adoptive mother knows nothing about this.

-Haruo loves books that don't make him think too much; he prefers easy literature despite being intelligent.

-He becomes humble, because although his adoptive mother does not treat him badly, he prefers street life because of his origins with his poor mother.

-Haruo has a personality that can be mischievous and daring, but he knows how and when to stop, by dissembling.

The white demon turns out to be related to Haruo's mother. According to the volume's spoiler summary, she had a relationship with a man who promised to stay by her side. They had Haruo, but that man ended up breaking his promise.
Later, the mother suffered a terrible ordeal on the bridge, being pushed by Haruo's father, but she survived. Her attachment to and suffering from that experience became intertwined with that story, and that burden eventually affected Haruo as well.
That's why Haruo wasn't simply waiting for a supernatural creature for no reason: his waiting is linked to his mother's past and the man responsible for that tragedy.

Wanting to torment his father at every opportunity, because he wants to make him feel guilty and remind him of what happened on that bridge.

One of the central questions related to Haruo is:
What does it really mean that he is waiting for the white demon?
The official synopsis of the third volume points out that the white demon is pursuing Haruo, while another description of the volume raises the question of what it means when Haruo says that he is waiting for said being.
Therefore, the relationship between Haruo and the white demon is one of the important mysteries of his character.

Haruo is a student in the dormitory who, despite leading a seemingly normal life, has a strange behavior: every night he leaves the dormitory to head towards the vicinity of the bridge.
When he appears in the story, Haruo mentions that he is waiting for the "white demon." This is intriguing because, at the same time, there is a mystery surrounding a ghost that appears on a nearby bridge.
Investigator Makoto, assistant to Detective Tōjō, begins investigating the case alongside Fuji, a writer who lives in Kaika. In the process, they meet Haruo and discover that his connection to the "white demon" is far more personal than it initially seemed.

Name: Haruo
Era: Late Taishō era (1912–1926)
Occupation: Student
First appearance: In the story of Kaika Apartment
Affiliation
Residence: Kaika apartment

Student.
He has a mysterious past.
He keeps his behaviors secret.
She leaves her apartment (where she lives with her stepmother and her father, who has already been arrested) during the night.
It is related to the mystery of the white demon.
Her story is linked to other residents.
His past still constitutes an important piece of the overall mystery.

Haruo is a young man with a delicate and youthful appearance, a slender build, and seemingly average height. He has thick, slightly wavy black hair with long bangs that fall over his forehead and partially cover his eyes. His face is refined, with large, dark eyes, delicate eyebrows, a small nose, and thin lips. His soft features give him a rather youthful and sophisticated look.

Haruo is introduced as a student whose past is deeply connected to the mysteries of the residents of the Kaika residence.
One of his most striking behaviors is that he sneaks out of his bedroom almost every night. He also talks about waiting for the "white demon," which directly connects his story to one of the residence's main mysteries.
This makes Haruo one of the characters who generate the most questions around the plot.