Eiji Nizuma is a high school genius mangaka who has been drawing ever since he was young. Moritaka Mashiro and Akito Takagi consider him their rival. He was supposed to serialize a manga titled Yellow Hit but he wanted to draw a different manga, Crow, which appeared in Akamaru Jump instead. His assistants were initially Nakai and Fukuda (Mashiro also worked for him temporarily before Detective Trap was serialized). His editor is Hattori Yujiro. He once demanded to be allowed to end one series he hated if he ever made it as the most popular author in Jump. Niizuma is slightly naive but can also be serious and calculating when he wants to. Eiji tends to act conceited because he is hailed as a genius; however, after working on Crow for quite a long time, he grew more humble, even claiming to not be "good enough of a mangaka to be judging other people's work" when asked by his editor to judge for the Golden Future Cup. (He judges anyway but is not very helpful, only expressing his interest in Ashirogi and Ryu Shizuka). Niizuma tends to make noises and sound effects when drawing or writing his manga. He is constantly chastised by his editor, and at first seems to be rather oblivious toward his rivals' feelings toward him, even expressing great excitement when he meets Ashirogi Muto and saying he is their fan. He is a great lover of manga and his opinion are valued by everyone at Jump, including his rivals. He refers to himself as an "Eternal Boy," and that is why he writes shounen manga.

Twenty-Fifth Bam (Korean: 스물다섯번째 밤; RR: Seumul-daseot-banjjae Bam; literal translation: Twenty-fifth Night) is the protagonist of Tower of God. Bam is the latest Irregular to enter the Tower, but because of his young age and naiveté, his abilities don't resemble those that previous Irregulars are known for. In the story, Bam enters The Tower in search of his best friend Rachel, the only person who visited him and cared for him in the years of isolation that he spent in a cave underneath the Tower. After entering the Tower, he is told that all the answers that he seeks will be answered if he climbs the tower, though he is immediately presented with a seemingly impossible and deadly test. Bam succeeds, and is allowed to move onto the second floor, where all would-be Regulars start their ascension. Throughout the webtoon, Bam makes several friends among the candidates, and together they pass the many tests of the floor.