Name: Ji-oh Gender: Male Age: Early teens Height: 150cm Nickname: Survival King The protagonist of the Survival Ji-oh series. He first appeared with Pipi and Kay in the Virus volume, the start of the Ji-oh series. Since then, he has appeared in every single volume released to date, serving as the longest-running protagonist of the currently serialized Survival series. Characteristics: A boy with the self-proclaimed and publicly recognized nickname 'Survival King'. True to his nickname, he is well-versed in survival common sense and has an instinctive sense for survival. Despite being an elementary school student, he possesses strong physical strength and mental fortitude. Due to the nature of the manga, he is destined to get caught up in all sorts of disasters and accidents every time, but he never despises his fate and overcomes crises together with the people around him. Comparison with previous protagonists: Compared to the Survival series published previously, he possesses much better intuition, physical strength, athletic ability, rational judgment, and common sense than most past protagonists. He responds calmly to any situation and always thinks positively. Unlike Leo, Duri, and Momo, the protagonists of past series who needed help from nearby adults, Ji-oh is a complete character who encourages other children even when no adults are present and survives steadily based on his abundant survival knowledge. While previous Survival series focused on stories where the protagonists saved their own lives in the face of crisis, Ji-oh often features stories where he saves the lives of others when a crisis strikes. He is frequently seen saving the lives of friends in danger or encouraging those around him in each volume. Even in the Allergy or Trash Island volumes, he steps forward to save others in danger even when he himself is not in a critical situation. Thanks to this, he has received favorable reviews mixed with jokes from fans saying, 'While the Survival seniors were busy saving their own lives, he travels around saving the world alone.' Nerfs: However, as the series continues, there are many cases where his personality or intelligence is nerfed. Starting from the Climate Change volume after the highly-regarded Virus volume, his nuisance character traits gradually strengthened, and from the Tidal Flat volume following the Human Body volume, his personality becomes so childlike and ignorant that one wonders if he is the same person as the Ji-oh from the Virus volume. Before the Tidal Flat volume, he also had the characteristics of a young child.

Gender: Male Age: 40s to early 50s Everyone calls him Doctor. A regular character in the Survival Ji-oh series. He is a frequently appearing supporting character, though not as much as the main trio of Ji-oh, Pipi, and Kay. He is a doctor and inventor appearing from the Human Body volume, a self-proclaimed genius doctor. He has Kay as his assistant. His real name is Noe Si-gyeong. He has a clumsy and easygoing personality and likes sweets. His main profession is a medical doctor (=physician), a type commonly seen in reality, but in reality, he invents all sorts of things, a type commonly seen in educational manga. He likes sweets (especially candy).

Name: Kay Gender: Male Age: Early to mid-20s Occupation: Medical student → Graduate student A character and sub-protagonist of the Survival Ji-oh series. He appears from the beginning of the work along with Ji-oh and Pipi. He is a total tsundere, nagging them or taking care of them and helping solve situations every time. In the work, he is mainly responsible for explaining scientific knowledge. A medical student who values cleanliness and safety like his life. [From the Forest Fire volume, he appears as a graduate student.] He has a prickly personality but is cowardly and has severe mysophobia. In the Virus volume, he had a phobia of blood but is said to have overcome it. In the Virus volume, he appears as a medical student who came to the jungle for medical volunteering, and from the Human Body volume onwards, he appears as Dr. Brain's assistant. He has a phobia of blood.