Previously on Conversion:

The world is in the grip of terror as creatures known as Jenemes emerge, draining human energy and youth to sustain their existence. Their victims, left lifeless husks, represent a dire threat to humanity. In response, the Tokyo government enacted a new law establishing the Jeneme Extermination Organization, or JEO, to protect the populace. Led by Semen Kisuke, commander of the Senior Affiliation (SA) unit, and Awara Somoshi, commander of the Under Affiliation (UA) unit, both under the guidance of expert scientist and inventor Gaieren, the JEO is humanity’s last line of defense.

Due to the scarcity of willing recruits, the JEO began enlisting agents as young as thirteen, up to twenty-five years old. As the organization grew, they discovered a few invaluable assets known as Star Bearers—individuals capable of summoning spirits through contracted objects to aid in battle. Among these rare Star Bearers were Riyu Kagaro, Ken Yone, and Jaienta Shimin. Kagaro, the youngest ever to become a unit captain, and Shimin were highly skilled agents, but it was Yone who possessed something truly exceptional: the star Satar, the strongest and most selective of all spirits.

After successfully quelling a Jeneme outbreak, UA Captain Awara introduced two new agents to JEO Unit 9, led by Kagaro. These agents, sisters Jenna and Momoko Ornard, were also Star Bearers—a rarity in the organization. Jenna wielded the enigmatic star Hibiki, while Momoko was assisted by Leeney. Kagaro, suspicious of the sisters' powers, confronted them harshly.

Meanwhile, Kagaro, Shimin, and Yone were undercover at Shinjuku School of Science and Technology, attending under false names while concealing their identities behind masks when on JEO duty. The secrecy allowed them to navigate the world without exposing their affiliation. However, when Jenemes attacked their school, Jenna's abilities were revealed to the agents in the chaos. Despite being wary of her friend Sonomo, who mysteriously knew a secret passage out of the classroom, Jenna did not investigate further.

During a later training session at the JEO headquarters with their new trainer Jento, a conflict erupted between Yone's star Satar and Jenna's star Hibiki. The resulting battle caused massive casualties and injuries, leading to the shutdown of the JEO Southern Unit.

Although the issue between the stars was eventually resolved, another crisis soon emerged. An attack by unrecognized A-type Jenemes devastated their school. Despite their efforts, Yone, Kagaro, Shimin, and Jenna were overwhelmed and suffered a crushing defeat. In the aftermath, the school and all JEO quarters were sealed and shut down, leaving the fate of the world uncertain.