In Re:ZERO -Starting Life in Another World- Season 4, The Pleiades Watchtower Riddle Was Built Only For Subaru?
The entire Pleiades Watchtower trial wasn't a general "hero's test." It was a trap door made specifically for someone from our world.
Fans picked this up in Episode 4 discussions. To even enter the library you need 3 things:
Earth knowledge: The riddle references constellations and specifically "Shaula" as Scorpio's tail. That's not common knowledge in Lugnica.
Aerial view: You need to fly over all the monoliths to see the pattern.
Language cues: Shaula and Flugel both use words/concepts from our world.
The Conspiracy angle: Flügel, the "Wise Man" Shaula calls Subaru, was also from our world. What if the Watchtower wasn't testing "heroes" — it was a message system left by Flügel for his reincarnation?
That would explain why Satella might see Subaru as Flügel. The tower was waiting 400 years for the right Subaru to come back, and Shaula was programmed to protect him on sight.
People think this is why the centaur mabeast was killed "to protect him" — Shaula recognized her master immediately