Senku Ishigami

Senku Ishigami is a young man of average build. His signature hairstyle features two bangs crossing his eyes, while the rest is sprayed down, like a plant. His hair is light, dirty blonde with tips that fade into a dark green hue. He has red eyes. After his de-petrification, he has two diagonal marks, mirrored one above the other, above the base of his eyebrows.

His clothing remains the same. Before the Stone Apocalypse, he wore his school uniform. In the Stone World, he switched to wearing rudimentary animal-skin clothing. After Yuzuriha's de-petrification, his clothing is redesigned. He wears the same animal skin, but this time in a caveman style, patched up in a more refined way. Albert Einstein's mass-energy equivalence formula (E = mc²) is printed on the front of his clothing, which serves as a "motto."

Senku has an over-the-top attitude that comes in the form of comedy and leadership. He is confident in himself and has the ability to back it up. Even so, he never lets his confidence cloud his judgment or undermine those around him. Rather, he serves as a source of encouragement and inspiration to everyone around him. Because of his resourcefulness and caring nature, people tend to rally around his colleagues and supporters alike. Although he has a strong sense of justice, he doesn't let rules dictate his actions and can sometimes be cunning to get what he wants. He often acts as if he builds inventions and uses people for his own interests and in the name of science, but beneath his arrogance and manipulative nature lies a genuinely kind heart. He goes against Tsukasa, stating that he would use science to save the seven billion petrified people.

In a flashback, when asked who he would choose between saving himself, his friend, or his lover, he replied that he would find a way to save everyone. He proves this to be true when he chooses to "sacrifice" himself to save his friend Yuzuriha from Tsukasa at the cost of revealing to the latter the ingredients and process for the elixir that would de-petrify stone statues. Similarly, he built a car for the express purpose of being able to transport elderly people with limited mobility despite claiming he did so for a faster trip to the enemy headquarters. He was even willingly going to walk into a very obvious trap set by Tsukasa to save Chrome (as Tsukasa knew he would never abandon his friends) though luckily Chrome skillfully managed to escape on her own.

Senku is a firm believer in science, believing that there is nothing that science cannot solve, but that science is a constant process that is a pain in the long process of understanding the rules behind the phenomenon.

He refuses to lie about anything related to science, as Tsukasa asked if Senku would promise to stop pursuing science and Tsukasa wouldn't kill him, Senku flatly refused. He will never lie when it comes to the capabilities of science (partly due to his own straightforward personality).

Senku is persistent in his endeavors, having initially worked alone for six months on the creation of the de-petrification elixir. He also has a habit of saying "ten billion possibilities" as his catchphrase when he is certain of something. He loves science and particularly loves creating new inventions. He will also use his accomplishments and inventions to win people over to his side, such as recreating ramen from scratch to win over some of the villagers to help him in his iron-making process. He tends to be deceitful and blunt in his opinions, which irritates some of his friends and makes him a terrible negotiator. Nonetheless, his intelligence, charisma, and compassion for his friends allow him to gain many allies and even move some of his enemies, especially Tsukasa.