Sagako Outbreak

The Sagako Outbreak (嵯峨子発生 Saga ko hassei) is the outbreak of Sagako Curses that happened during the mid-90s, which was dealt with accordingly by the Saga Sagako Busters.

Summary
Set in the '80s, long before that fateful day when a brave legendary girl was hit by a truck... is where another story, involving a different legendary girl, begins. For an onion farmer, an everyday day turns into a battle to save a cursed Saga.

Mid 80's
10 years ago, Saga's curse claimed the lives of Tae Yamada's parents, who were traveling to Saga presumably on a business trip that would make the prefecture known. Now an orphan, she is taken in by Jofuku who trains her to combat these curses and prevent them from claiming the lives of more people, although he himself is very overprotective with Tae and this causes their relationship to weaken little by little.

Years later, Tae meets Yuko during a battle in some desolate place in Saga, Yuko is willing to help Tae fight these curses and as time passes they become closer even working together a few years after meeting. To improve the effectiveness of the group, they look for new members together with Hanako and manage to attract Anna who mysteriously appeared in Saga, and although they do not know anything about her past life, the new member was very good support for the group by fighting the Sagakos intelligently.

Onions and Curses
Eikichi Hyodo works on the family farm after a shoulder injury prevents him from playing baseball and keeps him away from his friends, his twin sister Yuko Hyodo helps him harvest the the family and mentions how important onions are. The lives of both are completely different, Yuko works as an exorcist for a group of girls called Saga Sagako Busters, who are in charge of the curses that affect Saga constantly, but unfortunately Yuko perishes in a battle against a Sagako and now it will be the turn of her younger brother to combat these curses. After being kidnapped by the group and forced against his will to fight these curses, Eikichi gradually gains the "Misogi" power that allows him to properly seal these curses. As the weeks pass, the Sagakos become more powerful, with the introduction of Jofuku back to the group, he himself reveals to Eikichi part of the truth behind the Sagakos as beings that seek the destruction of Saga as a result of the search for an elixir of immortality in the past.

A false alarm of possession of a human by Sagako causes the group to accidentally attack Takeo Go thinking it was one of these curses, however, they weren't that far from the truth. Since in his school there is a Sagako that affects students who want to confess, Takeo is about to give up with his attempt to confess to Sachika but thanks to the efforts of the busters he achieves his goal of getting together with Sachika, relationship that years later would give rise to Lily Hoshikawa.

A mysterious man
The peace of the group is about to be affected by a man from Tokyo, Keiji Higashino, who came to Saga looking for the mystery behind Sagako's appearances. He meets up with Anna, a former fugitive whom he used to track down potential robberies in Tokyo several years ago. Although their meeting is somewhat abrupt, he manages to find what he came to look for, a Sagako whom he later eliminates. With Higashino on the loose in Saga, the group of Sagako Busters knows that he could get in trouble with the Sagakos and affect the operation of sealing all the Sagakos. While they decide to split up to search for Higashino, this operation results in failure when he brutally beats Eikichi out of action. Keiji continues with his plan to investigate the Sagakos and see what kind of creatures they are, he comes to the conclusion that these beings are not life forms but supernatural beings just as Anna had told him before, so he decides perform a test by launching a Sagako to the border with Fukuoka. This experiment concludes that these beings are limited only to Saga when the Sagako explodes shortly after leaving the border.

Sequels
The Sagako outbreaks take place 3 decades before the events of the anime, and thus there are still people in Saga who remember the times when the Sagakos roamed the prefecture and spread stories about them, which explains why almost everyone who they see the girls in their zombie states immediately label them as monsters. As for the various reactions to the supernatural of the girls, that could depend on the age of the characters.

Cops and rappers, who were young adults, wouldn't have existed when Sagako were prevalent, but they would have heard stories of monsters attacking people in Saga, so when a group of reanimated corpses move around at night, naturally your reaction would be: get scared In the second episode, the audience at Saga's castle barely reacts to Tae's head falling off, which they could attribute to special effects. However, since they would have been old enough to live in Saga when the Sagako prevailed, it is possible that they recognized Franchouchou as something supernatural, but since they were clearly not hostile, with Tae just eating the squid and not chasing the humans and thanks to Sakura and Saki's performance that inspired them to make the most of their lives with their rap, they decided not to make a fuss about it. The Hinasaka president in the bathhouse, like the old ones, would have been living in Saga during the Gaiden manga. Unlike the old men who would see the girls on a more neutral stage at a performance, the lady of the company had the misfortune to see the girls at night with them seemingly acting hostile (yelling and chasing after her). The fact that the bathhouse was apparently the previous site of a Sagako attack, as depicted in the Gaiden manga, would have only reinforced the lady-in-waiting's fear that these "beings" were clearly malevolent. Then there is Maimai who immediately recognizes the girls as zombies and accepts them. As the police, she would have heard stories of supernatural monsters roaming around Saga. Unlike the policeman, who had no idea who these zombies were, Maimai recognized them as Franchouchou and, being a fan of them she had been regularly attending their concerts and thus was not afraid of them; It also helps that she wasn't wearing her glasses, so she couldn't see her zombie forms clearly, which made them seem less hideous. Ultimately, the kids at the shelter didn't think Franchouchou were real zombies at all, ironically compared to the older characters. Being young children, they would not have existed when the Sagako existed in Saga and their families may have avoided telling stories about the Sagako to avoid scaring them into not knowing that real monsters like zombies could exist outside of fiction. Like Maimai, they would have gotten used to Franchouchou not seeing them as a threat, plus the zombie reveal that takes place during a performance makes it easy for Franchouchou to pass it off as zombie makeup.

Trivia

 * Sagako's outbreaks intensified proportionally to the more well-known Saga, the economic bubble of the late 80's that greatly affected Japan's economy also positively affected Saga, and since the power of the curse also depends on the power of prosperity of the prefecture, it eventually gained enough strength to manifest in physical form.
 * Both the prosperity and the curse gained a lot of power after Franchouchou's revenge concert and thus the supernatural phenomena in Saga were activated again, thanks to this, a Sagako manifested as a giant UFO destroying a city.