The luxury apartment has floor-to-ceiling windows, sweeping views of Tokyo Tower and a price tag of 880 million yen (S$7.1 million).

It also comes with a mysterious, green-suited entity scurrying from one room to another.

Or at least that was what viewers were left wondering after a Tokyo real estate agent posted a property tour featuring a person in a full-body, green-screen suit darting through the apartment.

In the June 15 video shared on Instagram, the person is seen opening doors and drawers, and sliding closets, before awkwardly scrambling out of frame.

“I’m sorry. I don’t know how to edit this green guy,” the agent, who posts under the name Japan Miho, wrote alongside the video. “I need editor maybe.”

The internet, naturally, was delighted. Many took the ball and ran with it.

“What green guy?” one user asked.

“How are the doors opening by themselves?” replied another.

“I kept repeating the video and couldn’t see it,” another wondered.

Others put in a well-meaning query with a wicked spin.

“Does this entity come with the place?” one asked.

There were some sceptics, though.

Visual effects artists were quick to point out that removing the figure from every frame is a painstaking and expensive process.

It requires extensive digital work to reconstruct reflections, shadows and portions of the apartment obscured by the suit.

“It is not impossible, but a crazy amount of work,” one comment said. “Would be cheaper to 3D scan the place.”

That has led many viewers to suspect that the green man was never meant to disappear at all.