Who Built the Pleiades Watchtower in Re:ZERO? Full Lore and Mysteries Explained

If there’s one location in Re:ZERO − Starting Life in Another World that completely changes how you view the series, it’s the Pleiades Watchtower. Arc 6 took Re:ZERO from a dark fantasy isekai into full-scale ancient mystery territory, and honestly, it’s one of the biggest reasons the series feels far more ambitious than most modern anime worlds.

At first glance, the tower looks like another dangerous dungeon hidden inside the deadly Augria Sand Dunes. But once Subaru and the others finally reach it, you quickly realize this place is far more important than a simple endgame location. Every floor, every trial, and every name tied to the structure points toward one unsettling truth: somebody from 400 years ago planned all of this in advance.

The deeper you dive into the lore, the stranger the entire tower becomes.

The Official Builders of the Pleiades Watchtower

According to the established Re:ZERO lore, the Pleiades Watchtower was created through the combined efforts of three legendary figures from the ancient era: Flugel, Reid Astrea, and the Divine Dragon Volcanica.

Character	Role in Construction	Importance
Flugel	Main architect and mastermind	Designed the structure and magical systems
Reid Astrea	Combat power and trial creator	Represents the martial challenge of the tower
Volcanica	Divine protection and sealing force	Guards the upper sections and ancient secrets

Out of these three, Flugel is very clearly the true creator behind the overall design of the tower. Reid feels like the ultimate weapon, while Volcanica acts more like the guardian protecting the structure. Flugel, however, appears to be the individual who understood the larger purpose behind everything.

After Arc 6, it becomes increasingly difficult to ignore the possibility that Flugel somehow knew Subaru would eventually arrive at the tower.

Why the Name “Pleiades” Is Extremely Important

One detail many casual viewers overlook is the significance of the tower’s name itself.

“Pleiades” is a real star cluster from Earth astronomy and mythology. In Japanese, Subaru’s own name directly refers to the Pleiades constellation. That detail alone already raises massive questions about Flugel’s identity.

As the story continues, even more suspicious clues begin appearing:

The tower floors are named after stars
Flugel used Earth-like astronomical naming systems
Subaru immediately understands references nobody else recognizes
The structure itself contains logic-based systems unlike normal fantasy magic

This is where one of Re:ZERO’s most popular theories begins gaining serious weight: Flugel may have been an otherworlder from Earth, just like Subaru.

For many anime fans, this is the exact point where Re:ZERO transforms from a dark fantasy story into something far more layered. Suddenly, the lore becomes filled with possible time paradoxes, reincarnation theories, hidden timelines, and connections spanning centuries.

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The Tower Was Never Just a Building

What makes the Pleiades Watchtower so fascinating is that it was never designed as a normal fortress or dungeon. The structure behaves more like a giant magical system built for a specific long-term purpose.

Each floor serves a different role within the tower:

Floor	Purpose
Asterope	Residence of Volcanica
Electra	Combat trial connected to Reid Astrea
Taygeta	The Library of the Dead
Maia	Living quarters and support areas
Merope	Main defensive entrance layer
Alcyone	Hidden underground systems and mechanisms

The most terrifying location inside the tower is easily the Library of the Dead. This area completely changes the scale of the Re:ZERO universe. The existence of books containing the complete memories of dead individuals introduces concepts that go far beyond ordinary fantasy magic.

The library appears directly connected to Od Lagna, the source of souls and mana within the world. The fact that Flugel was capable of creating such a system demonstrates an absurd level of magical and conceptual knowledge.

At that point, the Watchtower stops feeling like fantasy architecture and starts feeling like reality manipulation.

Shaula Was Never the True Sage

For centuries, people across the world believed that the Great Sage Shaula created the Pleiades Watchtower. However, Arc 6 completely destroys that assumption.

When Subaru finally arrives at the tower, Shaula immediately recognizes him as her “Master,” creating one of the most shocking moments in the series.

Instead of being the wise ancient sage everyone expected, Shaula is revealed to be a loyal guardian left behind by Flugel himself.

She spent 400 years completely isolated in the desert, following her master’s orders without question. During that time, she killed countless travelers attempting to reach the tower because she had been instructed to eliminate anyone who failed to meet the required conditions.

Honestly, Shaula’s story is one of the saddest pieces of Re:ZERO lore. Beneath her cheerful personality is a character defined entirely by loneliness, loyalty, and abandonment.

The most important detail, however, is that she does not mistake Subaru for someone similar to Flugel. She reacts as if Subaru himself is the master she had been waiting for all along.

That single moment remains one of the biggest reasons the community continues connecting Subaru and Flugel together.

The Watchtower Feels Almost Technological

One of the most unique aspects of the Pleiades Watchtower is how advanced its magical systems feel compared to the rest of the Re:ZERO world.

Inside the tower are automated defense systems, magical barriers, rule-monitoring monoliths, and punishment mechanisms that function almost like computer programming.

The green monoliths are especially fascinating because they actively track the conditions of each trial. If someone violates a rule, the system immediately responds with lethal consequences.

Leave the tower during a challenge? Punishment activates instantly.

Break a condition during a trial? The system automatically responds.

This style of logic feels less like traditional fantasy magic and more like coded security protocols. Many fans believe Flugel combined magic with Earth-style logical systems in order to create something completely alien to the people of that world.

That would explain why the tower feels so unnatural even to extremely powerful characters.

The Real Purpose of the Pleiades Watchtower

After years of fan theories and lore discussions, most readers generally agree that the Watchtower serves three major purposes.

1. Maintaining the Seal of Satella

The most obvious purpose of the tower is helping maintain the seal on Satella, the Witch of Envy. Together with the Augria Sand Dunes and surrounding barriers, the Watchtower acts as part of the ancient system preventing catastrophe from returning to the world.

2. Preserving the True History of Humanity

The Library of the Dead functions like an eternal archive of human existence. In a world where memories, names, and even identities can disappear, Flugel created a place where absolute truth could still survive.

Even if history becomes distorted outside the tower, the memories stored inside remain untouched.

That idea alone makes the Watchtower one of the most terrifying and brilliant creations in the entire series.

3. Testing Subaru Natsuki

The most compelling theory surrounding the tower is that it was specifically designed for Subaru.

Many of the challenges inside reward abilities Subaru uniquely possesses:

Understanding astronomical references
Thinking with modern-world logic
Solving impossible situations through repetition
Adapting after failure

Combined with Shaula’s reaction to Subaru, the evidence increasingly suggests that Flugel expected Subaru to eventually arrive at the tower one day.

Is Flugel Actually Subaru?

No discussion about the Pleiades Watchtower is complete without mentioning the massive theory connecting Flugel and Subaru.

The similarities between them are difficult to ignore:

Similarity	Flugel	Subaru
Connection to stars	Yes	Yes
Knowledge from Earth	Strongly implied	Confirmed
Possession of Witch Factors	Yes	Yes
Connection to Satella	Yes	Yes
Linked to Shaula	Yes	Yes

Some fans believe Flugel is a future version of Subaru connected through time travel or reincarnation. Others believe the two simply share some deeper spiritual bond tied to Od Lagna and the Witch Factors.

At this stage of the story, either possibility still feels believable.

Re:ZERO constantly explores themes involving identity, memory, souls, and distorted timelines. Because of that, the theory no longer feels impossible.

Final Thoughts

The Pleiades Watchtower is easily one of the greatest lore locations in modern anime fantasy because it combines nearly everything that makes Re:ZERO special.