This painting depicts coal mine carpenters constructing wood frames to support a driveway ceiling.
Each frame stood 1.5 meters apart.
When the prop cracked from pressure, an extra frame, called "Ma-waku", was added in between to support it.
On the left side of the painting, a man is fixing a pillar to the frame without digging a hole on the ground.
Since they couldn't bear the pressure of the ceiling, such pillars were called "Ningyo-waku", or fake pillars.
Sakubei called the people who did this kind of work irresponsible.