By forbidding change, Kawaguchi implicitly critiques the Western, technocratic fantasy of time travel as mastery. In films like Back to the Future or Avengers: Endgame , the protagonist wields time as a tool. In Kawaguchi, time is a wall. The only thing that can cross it is speech —the spoken word, unaltered and often unheard by the intended recipient.

The phrase "Hasta el próximo café" (Until the next coffee) serves as a beautiful metaphor for hope—the idea that as long as we have more days (and more coffee), we have another chance to say "I love you" or "I’m sorry."

However, this is no typical science-fiction adventure. The rules are strict and serve as the emotional core of the narrative. Travelers can only sit in a specific seat. They cannot leave the café during their journey. They cannot change the past, no matter what they see. And the most crucial rule: they must return to the present . Breaking this rule means being trapped in time forever as a ghost, still seated in the café, serving coffee for all eternity.

No matter what you do in the past, the present will not change.