Kyōka's Parents vs. Unnamed Assailants

Kyōka's parents vs. unnamed assailants is a battle fought between Kyōka Izumi's father and mother against unnamed assailants being controlled by an unknown ability user.

It happened three years ago in the Izumi family house. The incident also marked the transfer of Demon Snow to Kyōka from her mother.

Prologue
One night while Kyōka plays outside during a full moon, Kyōka's mother prepares supper, which Kyōka's father warmly praises having and being with the two of them. Some assailants soon silently loom from the shadows of the house.

Battle
As an assailant aims to attack Kyōka's father from behind, the latter effortlessly throws a blade at the assailant and later kills them. He switches to his pistol and shoots two attackers hiding in the ceiling. Kyōka's mother then activates Demon Snow and beheads another assailant behind her.

When some blood lands on Kyōka's father's face, he immediately attacks his spouse, though Demon Snow blocks his blade attack. He surmises that he is being controlled through blood by an external party; as the young Kyōka looks inside the house, her father asks his wife to kill him, so Demon Snow slashes him to death.

Before the shocked Kyōka, some blood on her father splatters on her mother's face. The body possession ability activates once more and controls her mother, so she orders Demon Snow to protect her daughter. The ability then stabs Kyōka's mother, who imparts her final words to her daughter and soon dies, leaving Kyōka aghast.

Aftermath
Kyōka's parents turn out to have been killed by a vengeful ability user. Since both her parents are former assassins affiliated to the government, the latter is unable to disclose them to the public. Hence, the incident is covered up to have been caused by an ability gone out of control. However, the entire event is nonetheless documented by the Special Division for Unusual Powers.

Moreover, after the incident, Kyōka gains Demon Snow as her ability, which her mother had apparently transferred to her at the last minute. However, it was an incomplete transfer, hence requiring Kyōka to control Demon Snow only through her phone that was given to her by her mother days before the incident.

Manga and Anime Differences
Contrary to the manga where Kyōka's father throws a blade to his first attacker, the anime portrays him shooting the assailant behind him. Furthermore, her mother beheads an enemy in the manga, while she severs their arm in the anime. Kyōka's father also seems to have shot two assailants hiding in the ceiling in the manga, while he appears to shoot only one in the anime.

Prior to getting affected by the body possession ability, the anime adds Kyōka's father shooting an assailant at point-blank range, whose blood splatters on his face, and tries to resist shooting Kyōka nearby, with which Demon Snow slashes him from behind. The manga leaves the source of the blood ambiguous, and he further tries to attack his spouse, which gets blocked by Demon Snow. He also manages to almost attack Kyōka with his blade before getting slashed to death.

In the manga, Demon Snow almost immediately kills Kyōka's mother after the latter orders it to protect Kyōka. In the anime, she is portrayed to still wield a blade hidden in her before Demon Snow gets transferred to Kyōka and stabs her.

As a minor difference, the assailants in the anime are portrayed wearing black garb reminiscent of the archetypal and being apparently manipulated by the body possession ability as shown through at least one of their eyes, but the manga depicts them having no distinct uniform. While the anime portrays the body possession ability host's eye having a reddish hue and glow, the manga does not illustrate this and shows the controlled person retaining a similar ocular appearance.