Tomiyama is a short boy with wavy beige hair, prominent black eyes, and a large closed-mouth smile. He is commonly seen wearing the Shishitoren jacket over a white shirt that has a Route 66 logo (or a smiley logo with the text

"Smile" in the official video game), a pair of black sweatpants, and rubber shoes for footwear. His rubber shoes are white-bordered and red with an orange T-design on it, T being the first letter of his surname, with blue laces.Tomiyama is a strong fighter who is quick to challenge others and does so with an overjoyed attitude. He initially strived to be at the top of the hierarchy to fulfill his desire to become happier and freer like Hajime Umemiya, believing that greater power was used to attain greater freedom.

Whenever his philosophy was challenged, he became stern with his commands, acting indifferently toward his men. He expelled those he saw as weaklings from Shishitoren and challenged people who held great power in order to achieve his vision for the team.When Tomiyama first joined Shishitoren with Jo Togame, they were told that power was used to attain freedom and that they must persist through tough times to prove themselves as strong.

Despite being newcomers, he and Togame went against a rival gang called Zinc, whom they defeated for Minoru Kanuma, their ally. Togame deemed Tomiyama fit as Shishitoren's first-in-command who could transform it for the better, but Tomiyama had conflicting views. When Tomiyama rose to power as leader, he was unsatisfied with the role and found it dull, prompting him to create a team as strong as himself. He expelled those who sought his help from the gang, treating them as "weaklings" for failing to persevere on their own, and he threatened to expel Togame unless he followed his new direction.Tomiyama's fighting prowess is incredibly frightening, his strength matching Umemiya's. His fighting skills paved the way for his promotion to leader of the Shishitoren, despite being a rookie in the gang. He easily defeated Ren Kaji and the other members of the Bofurin. The only one capable of defeating him is Hajime Umemiya.
He is an incredibly fast, acrobatic, and flexible fighter. His agility makes him difficult to react to blows, and his acrobatic movements allow him to quickly regain his balance for precise strikes. With his extraordinary speed and fighting sense, he becomes skilled and strong in punches, aerial and circular kicks, feints, low dodges, and ground acrobatics reminiscent of Sakura fighting style.

• Acrobatics and Agility: Choji is capable of performing fluid and acrobatic movements, moving quickly to attack his opponents from above, below, and at blind angles, as shown in his fight against Umemiya, even though he lost.He likes cheap confectioneries and clothes without a lot of fabric (he seems to like tight-fitted pants).

• He hates fish (bones).

• He apparently loves sweet drinks.

• He uses a drawstring purse as a wallet; he packs all of his receipts into there.

• He seems to really like sneakers ("They are unique!").

• He has naturally wavy hair; he does not do anything special to maintain it.

• Although he buys clothes at random, he seems to really like his shirts.

• He loses things constantly.

• He only says whatever he wants to say and rarely answers other people's questions.

• He is a self-proclaimed cat whisperer.