A mobile unit belonging to the WHO Korea branch. They operate a force of approximately 1,000 personnel. There are 100 teams in total, with 10 members per team. They are equipped with suppressed assault rifles, special helmets that cover the entire face, night vision goggles, and black uniforms with 'WHO' printed on them.

An armored unit belonging to the WHO Korea branch. This is an armored unit consisting of 200 personnel. There are 20 teams in total, with 10 members per team. They operate 30 armored vehicles and 10 tanks. "Unlike other units, each team in the armored unit has a name. Examples: Bravo Team, Alpha Team, Delta Team, Cobra Team, Echo Team, Charlie Team, etc. (Armored unit only!!)" They are equipped with suppressed assault rifles, special helmets that cover the entire face, night vision goggles, and black uniforms with 'WHO' printed on them.

The air force belonging to the WHO Korea branch. Consisting of approximately 150 personnel, they are one of the busiest units in the human reconstruction personnel recovery operations. They can operate 25 WHO transport helicopters and approximately 5 attack helicopters. Originally, the air force was supposed to handle all recovery operations, but due to the sheer volume, many cases are handed over to the WHO mobile or armored units for authorization. They are equipped with suppressed assault rifles, special helmets that cover the entire face, night vision goggles, and black uniforms with 'WHO' printed on them.

The team responsible for the security of the WHO Korea branch. Consisting of approximately 70 personnel, they handle internal security within the Korea branch. They are equipped with suppressed assault rifles, special helmets that cover the entire face, night vision goggles, and black uniforms with 'WHO' printed on them.

A Colonel in the Republic of Korea Army who served as the commander-in-chief of the Forward Operating Base in charge of Gyeonggi-do during the initial infection outbreak.

A leading authority in the field of virology at the Institute of Science and Technology.

A civilian force armed with hunting rifles stolen from destroyed police stations. They sometimes monopolize survival supplies in specific areas and protect civilians in their territory from zombies.

Code Name: Yui Team leader of the Special Operations Unit (SOU) belonging to the WHO US branch, i.e., Headquarters. She possesses highly superior, overwhelming killer-level martial arts skills and is proficient with all weapons. Yui (female) is an SOU member directly under Headquarters, dispatched a month before the Sillim-dong incident to assess the overall situation in Korea. No one except the command team at the US Headquarters knows the location of the SOU. (SOU members know each other's faces but cannot track each other's locations.) She is an immeasurable asset highly cherished by Headquarters.