As per tradition of the Megami Tensei franchise, he is a silent protagonist, whose personality is based on the player's actions and decisions. However, he appears to have more established traits than any of the previous protagonists. His dialogue options range from somewhat indifferent to outright cheeky. The game allows for quite a number of playful, snarky or audacious answers, including teasing his friends. He also taunts his enemies like the famed Arsène Lupin. In the prologue scene, he remains cocky and confident even when his life is in danger. He also has a flair for showing off and making dramatic decisions, such as exiting by jumping through the stained glass windows of the Casino, much to the amazement of the other Phantom Thieves. This is even reflected in gameplay, as when he is turned into a mouse, he makes a flamboyant hop after escaping a battle.

Munehisa Iwai says if everyone in the world held the same code of honor as the protagonist, guns would be obsolete. Sadayo Kawakami notes that, by opposing Suguru Kamoshida, he has a strong sense of justice despite his bad reputation. Shinya Oda states that he made him realize "To be cool, you have to live life in your own way." and that's the type of person he's striving to become. Hifumi Togo notes, while playing Shogi with him, that she senses he has a "gambler's spirit." Sojiro Sakura says the protagonist has an assertive nature, to which the rest of the thieves agree. During the climax of the Niijima Palace heist, Ryuji Sakamoto states that despite being quiet, once he has made up his mind, he won't take no for an answer. Goro Akechi says although the protagonist is quiet, he possesses the courage and determination to take action, and has a free heart, despite his social standing and how others view him, and that he never stops choosing his own path.