Re:ZERO’s Pleiades Watchtower tests visitors with Earth’s constellations, keeps the Books of the Dead and holds Shaula, who calls Subaru her master. Was it built for him? An Arc 6 theory.
Imagine reaching a legendary tower in another world, only to find an entrance exam that expects you to know Earth's constellations. That's not a fair test. That's a quiz designed to fail almost everyone in the room.
Unless almost everyone was never the intended audience. What if the Pleiades Watchtower's strange star clues were meant to catch the attention of someone like Subaru? Maybe the tower is less a dungeon and more a message waiting four hundred years to be opened.
Major Arc 6 spoilers ahead. The idea that Flugel is a future Subaru is a fan theory, not an established answer.
An exam that only makes sense if it has a recipient
The tower uses star names and a trial connected to knowledge Subaru brought from Japan. The clues feel wildly unfair to people who have never seen Earth's sky or heard its mythology.
As a public exam, that's terrible design. As a sign left for a particular successor, it's much more intriguing. The star puzzle might be asking not “Are you clever?” but “Are you the person I was hoping would arrive?”
That doesn't prove Subaru was the intended recipient. It does explain why the puzzle is so oddly specific.
Why keep a library of the dead in a watchtower?
The structure is also known as the Great Library Pleiades. Behind its trials are Books of the Dead, linked to the memories of people who have died. Arc 6 makes those records intensely personal for Subaru.
A tower built to preserve knowledge, challenge visitors and protect access to records sounds like an elaborate way to pass information across generations. It begins to look less like a guard post and more like an archive with a very strict reception desk.
But don't make the next leap too quickly. The existence of death records does not prove that the tower stores every Return by Death loop, or that Flugel programmed the whole system for Subaru. Those are additional theories.
Flugel's clues are suspicious, not conclusive
Flugel appears to have knowledge connected to Earth. He also left the wonderfully childish “Flugel was here” message on the great tree. Subaru recognizes the impulse. Ancient sage or student signing the wall on a school trip?
Shaula then mistakes—or recognizes—Subaru as her master. Put those scenes together and the future-Subaru theory becomes tempting: maybe Subaru travels to the past, becomes Flugel and builds something his younger self will need.
It's a neat possibility. It's not a verdict. Flugel could be another person with Earth-linked knowledge. Shaula could be identifying a scent or some other trait rather than a face. Neither clue independently establishes time travel, and neither proves Emilia is Satella.
A handoff is more interesting than an answer key
Suppose Flugel did leave something behind for a future visitor. It might not be a solution. It could be a note saying, “Here's how far I got. You decide what happens next.”
Arc 6 already explores Subaru meeting the traces of his own life from a different perspective. The thought that the whole tower is a bigger version of that idea has real narrative appeal.
For now, the mystery stays open. We know the tower contains strange trials and an extraordinary library. We don't know who its hidden message, if any, was written for.
Still, imagine spending four hundred years delivering a password hint. A little excessive. Then again, the fantasy world hadn't invented email.
Check the source chapters
- Arc 6, Chapter 20: https://ncode.syosetu.com/n2267be/422/
- Arc 6, Chapter 22: https://ncode.syosetu.com/n2267be/424/
- Arc 6, Chapter 74: https://ncode.syosetu.com/n2267be/480/
