Outside the underground city of the Greater Rats, there was a rail through the main underground passages.
Trains full of supplies sped through the rail periodically.
Lights blared on the sides of the rail, where fully-armed soldiers would patrol.
Different from above-ground, sky, and naval battles, most underground battles were fought in dark and narrow tunnels, which made them dangerous.
In every nook that light could not reach, there was a chance that someone could land a fatal strike to another.
Bai Shifu was taking Chong Daqing on a patrol on this brightly-lit main passage.
Naturally, the main passage was the aorta of the city.
They could give up on everywhere else except for this passage.
The main passage was the connector of several underground farms that were close to the aquifer. Utilizing the cheap geothermal energy, they could soillessly produce a large number of vegetables, grains, and all sorts of fruits.