Yuri, who has lost their memory, wakes up aboard the Interstellar Cruiser D.Q.O. They are taken by Setsu to participate in a meeting to identify the "Gnosia," a being that attacks and annihilates humans.

Yuri, who looped back to the first day, attends the meeting knowing who the Gnosia is. Yuri tries to cast suspicion on SQ, but the discussion doesn't progress as expected...?

Shigemichi and Stella join the group, and a meeting is held with seven people. During the meeting, Yuri uses their intuition to identify the Gnosia, but they struggle to convince the other crew members.

Despite identifying the Gnosia and surviving, Yuri finds themself back at the first day in a daze, when a person with an unusual presence, Yuriko, appears before them. She seems to know something, but...?

New crew members Comet and Chipie join the meeting. Two of the crew claim to be engineers, but Racio argues against voting for them, resulting in the votes going to...?

Yuri attends the meeting in a new role as the "Guardian Angel." With Jonas and Kukrushka joining, the meeting now has 13 people, and as the situation becomes chaotic, one crew member raises their hand.

Otome and Remnan join in and the meeting is about to begin, but the other new crew member, Sha-Ming, refuses to come out of his room. Meanwhile, Shigemichi begins to talk about his feelings for Stella.

Remnan and Kukrushka step forward as "Guard Duty," a role that confirms they are human. As the number of positions increases and the meeting becomes more complicated, Sha-Ming, who is suspected by Kukrushka, takes a certain action...

Yuri awakens as a Gnosia. Though they feel hesitant about deceiving their fellow crew members, they are touched by the feelings of Comet, who shares their position, and resolve to fulfill their role as promised to Setsu.

Yuri, who has looped once again, is astonished by their new appearance. Amidst this, the meeting is postponed due to Sha-Ming's absence, and Raqio reveals the secret of the Silver Key to the bewildered Yuri.

Upon waking up, Yuri finds themself in a loop where they and SQ are on Guard Duty. Knowing that they are both human, the two grow closer, and eventually SQ reveals her true "identity"—.

Gina, who intensely dislikes lying and deceiving others, is confided in about the loops by Yuri. Recalling a painful past, she expresses her fears and resistance toward becoming a Gnosia.

Before the meeting, Setsu loses consciousness and is taken to the Sickbay. As they share the information they have acquired, Yuri suggests that Setsu, who appears exhausted from having repeated hundreds of loops, take a break. The "Truth Arc" begins...

"If you survive this loop, I'll tell you everything." Yuri, presented with a condition by Yuriko, attends a meeting where all 15 crew members are gathered. However, once the meeting begins, an unexpected proposal comes from Yuriko.

Raqio, who was identified as a Gnosia by the Engineer, Yuri, claims innocence based on a certain action. The emergence of an AC Follower throws the meeting into chaos, and Yuri is cornered.

When Yuri awakens, it's in a world line where the ship has escaped Gnosia contamination. As Yuri is bewildered by Kukrushka's implication of "the end of the universe," an alarm blares detecting an abnormal biological reaction.

Yuri learns the truth: that they are a "Bug" that shouldn't exist. They struggle to escape the time loop and the cosmic collapse caused by their dual existence, but...?

Yuri awakens on "DAY 0," the day before the loop they always experience and before escaping Liu-An. They meet Setsu there, but Setsu seems unaware of the Silver Key or the loops...

Yuri has escaped the loop, but the crew members have lost all memory of Setsu. On the planet where they land, Yuri follows Setsu's traces, only to be confronted with the harsh fact that Setsu's very existence has vanished.

In order to end Setsu's loop, Yuri obtains Raqio's "Silver Key." As Yuri tries to host the key once again, Raqio calls out to them.

Yuri reunites with Setsu on the other side of the dimensional door. They find themselves in the world line before they received the Silver Key that first awakened them. And so, their final discussion begins――