The prison has a tall gate and tall walls with barbed wires. The building is heavily monitored with cameras on different locations with large monitors for the guards to see. For more difficult prisoners like Speed-o'-Sound Sonic, they use a special restraining device designed by the Hero Association. The cells that hold the most difficult prisoners is behind a thick, barricaded door. Inside are the most difficult offenders, who can use their strength to pry open iron bars or can use everyday objects as weapons and poison. The inside of the walls are made of steel and there are no windows, and only Puri-Puri Prisoner can break through the walls.
|Cities||A-City • B-City • C-City • D-City • F-City • G-City • H-City • I-City • J-City • K-City • L-City • M-City • N-City • O-City • P-City • Q-City • R-City • S-City • T-City • U-City • V-City • W-City • X-City • Y-City • Z-City|
|Locations||Bang's Dojo • Final Training Ground • Hero Association Hospital • King's Apartment • Monster Association Headquarters • Mouse Sushi • Ninja Village • Saitama's Apartment • Smelly Lid Prison • Z Police Station • Z-City Ghost Town|