There is a red self-explosion sign on the window.

Japan has dense buildings and narrow streets. Fire prevention is an important task, and the "Red Triangle" is specially prepared for firefighters.

Once the building is on fire, firefighters will choose the window with the "red triangle" to enter the building, because the window with the "red triangle" has been specially treated to facilitate the broken window. For people in the building, once they find a fire and can't escape, they will also run to the window with the "red triangle" because this will be the first place to meet firefighters.

This method is not only implemented in high-rise buildings, but also applicable to expressways. On both sides of the closed expressway, emergency exits marked with red triangles will appear at regular intervals.