Crystal Tokyo has existed in peace for centuries-so peaceful that there hasn't even been a need for Sailor Senshi to defend it. Ever since they were reborn through the power of the Galaxy Cauldron the senshi have lived peaceful lives as Neo-Queen Serenity's court. However, the peace is shattered when one final servant of Chaos possesses Hotaru, and now they must fight one last time, facing some uncomfortable truths in the process.
Cosmos Arc is a continuation of Sailor Moon done by VivianexMoon. Unusually for a web comic, it isn't drawn by her, but brought to life using the canonical artwork in the manga (and at least one other work by Naoko Takeuchi) and Photoshop. It's meant to explore some of the ramifications of Usagi's choices in the manga, and answer a question that's existed since the end of Sailor Moon: just who is Sailor Cosmos?
A prequel, Chaos Arc, detailing the origins of Chaos and Queen Serenity's tenure as a senshi, had been planned, but will only be posted as artwork and a condensed version as the epilogue to Cosmos Arc as VivianexMoon wishes to concentrate on other projects for now.
Warning: Unmarked spoilers for the end of Sailor Moon below.
This work contains the following tropes.
- 11th-Hour Superpower: Usagi ascending to Sailor Cosmos caused the other senshi to ascend to their cosmic forms, and Chibiusa's powers to finally awaken as Neo Sailor Moon. It also breaks Hotaru's brainwashing so she could become Cosmic Sailor Saturn.
- Abdicate the Throne: After Usagi ascended and Chibiusa awakened, Mamoru relinquished his claim to the throne to take over Helios's job as priest of Elysion, so Helios could go to Chibiusa.
- Abstract Apotheosis: This is ultimately what Sailor Cosmos is: the embodiment of hope in the universe. Likewise, this is what Chaos is: the embodiment of despair.
- Ascend to a Higher Plane of Existence: Usagi and most of the other senshi do this. Hotaru is the only one that doesn't, in order to be part of Neo Moon's team.
- Balance Between Good and Evil: The whole thing started because Usagi tried to ignore that this existed. By trying to pretend that evil can be completely eliminated, she left Chibiusa unprepared for fighting and vulnerable to Servant Chaos.
- Be Careful What You Wish For: Chaos wanted to merge with Usagi in order to become Sailor Chaos. Chaos did merge with Usagi...after she became Sailor Cosmos.
- Bittersweet Ending: Chibiusa finally awakens as Neo Sailor Moon and prepares to assume the throne, but her father is now a priest in Elysion and her mother has ascended to basically godhood, not to mention that Helios isn't even sure she wants him by her side. And of course, there's Usagi becoming the embodiment of hope in the universe at the cost of her physical existence.
- Brainwashed: Chibiusa is brainwashed by Servant Chaos to be a queen that will usher in a new era of chaos. Then Endymion is possessed as well to be Chibiusa's consort. Then Servant Chaos brainwashes the Asteroid Senshi to be their fighters.
- Break the Cutie: The reason they didn't just kill Usagi outright: they want her to push past the Despair Event Horizon and be willing to merge with Chaos.
- Cassandra Truth: In the past, Ikuko had been tricked into thinking that Chibi Chibi was her daughter. She was, in a technical sense.
- Curse: The other senshi are cursed by Chibiusa and Endymion to be ghosts that nobody remembers during the day, but human at night.
- Demonic Possession: The story starts with Hotaru getting possessed by Servant Chaos.
- Despair Event Horizon: Servant Chaos's entire goal is to drive Usagi to this point so she'd be willing to merge with Chaos. Being forced to fight her daughter and husband, accidentally killing the Asteroid Senshi, realizing that peace will never last and finding out all this was unconsciously her fault for wishing Chibiusa never awoke as a senshi did the trick.
- FaceHeel Turn: Sort of. Usagi concludes that the only way to stop the cycle of good and evil is to destroy the Galaxy Cauldron and destroy the universe. She's talked out of it by her past self.
- Hotaru ends up on the side of evil again thanks to Servant Chaos possessing her.
- For Want of a Nail: Because they were reborn through the Cauldron, Crystal Tokyo was founded in the 30th century instead of the 21st. This also seems to have had an effect on Chibiusa, as she never awoke as a senshi. It's revealed that it's because Usagi secretly wished that Chibiusa never became a senshi so her daughter can live in peace.
- The Future: Cosmos Arc takes place in the 60th century.
- Gilded Cage: Usagi realized she created one of these because she no longer wanted to have to fight.
- Luna, Artemis, and Diana are trapped in the restored Moon Palace thanks to Chaos.
- Killed Off for Real: The Starlight Senshi were confirmed to not have been revived, as were any other senshi who represented a destroyed planet.
- Laser-Guided Amnesia: Part of the brainwashing involves Chibiusa and Endymion forgetting who Usagi was. As far as they were concerned, Chibiusa had always been the queen, and Endymion her husband.
- Matricide: Usagi let Chibiusa did this. It ends up breaking Chibiusa and Endymion's brainwashing.
- My Future Self and Me: what Usagi and Chibi Chibi turn out to be doing. The past Usagi never finds out, but Chibi Chibi knows.
- Parental Incest: Endymion and Chibiusa are brainwashed into believing they're husband and wife, not father and daughter.
- Past-Life Memories: Chibiusa slowly starts getting back the memories of her past, time traveling self as Helios tries to reach her.
- Race Against the Clock: Since they aren't powerful enough to Sailor Teleport, and it'd be dangerous to try to get to the Space-Time Door, the senshi have to hurry and fly to the portal to Elysion before the sun goes down and they lose their wings, dooming them to drown in the ocean.
- Reincarnation: After the other senshi throw her Sailor Crystal into the Galaxy Cauldron, Usagi is reincarnated as Sailor Chibi Chibi.
- Retcon: Initially Servant Chaos was basically a slightly altered Mistress 9. She was later changed to have Mistress 9's hair, but Saturn's princess dress. Dialogue was also changed to make more clear exactly what happened that caused the time-traveling Chibiusa to never exist.
- Sadistic Choice: Chibiusa presents Usagi with three choices: watch Chibiusa kill the other senshi, be forced to kill her own daughter, or join Chaos. Usagi lets Chibiusa kill her instead.
- Spared by the Adaptation: The last they were seen in the canon manga, Luna, Artemis, and Diana were killed by Sailor Lethe and they weren't seen revived at the end, with their fates up in the air. Cosmos Arc reveals they were indeed revived and now lived in the former Moon Kingdom in their humanoid bodies.
- Stable Time Loop: Usagi chooses to go back in time as Chibi Chibi to convince her past self to destroy the Galaxy Cauldron. This, of course, leads to the canon events.
- Suicide by Cop: Rather than have to make the Sadistic Choice, Usagi lets Chibiusa kill her. It breaks Chibiusa's brainwashing in the process.
- Temporal Paradox: Ok. Because the canon Chibiusa was present at the final battle temporarily, she ended up reborn as well as the other senshi. However, since she was now born in the 30th century instead of the 21st century like in canon, the Chibiusa of Cosmos Arc never traveled through time or awoke as a senshi, leaving her untapped power a juicy target for Servant Chaos. It's Usagi's fault, she had wanted Chibiusa to never have to awaken.
- What the Hell, Hero?: The other senshi after Usagi losing her temper resulted in her killing the Asteroid Senshi. This turns out to be one of the things that pushes Usagi over the Despair Event Horizon.
- Worf Had the Flu: The senshi haven't fought in so long that their fighting prowess has stagnated. And given how they technically never fought in this lifetime since being reborn, they weren't even sure if they could transform at first.