Goa Jepang No. 4 sits furthest to the north along the defense line, located about 142 meters northwest of Bunker 3.
This rectangular structure measures roughly 3.5 meters long and 3.1 meters wide, with its main entrance facing directly east. Like neighboring structures, it features sturdy coral limestone side walls and a smooth plastered cement floor inside.
The functional layout includes a distinct ventilation shaft carved into the northern ceiling, making it one of the most mechanically interesting bunkers to photograph on the trail.
Also read the main article about Kawasan Goa Jepang.
