Tatsuki, known affectionately as Tatsukichi by Ran, is a lively and kind-hearted student at Machida West High School. He proudly calls himself the "parapara king of Machida," but he's also known as "Machida Black" due to the meaning of "kuro" in his last name, which translates to "black." In the manga, his surname is literally translated as Blackwell. Often nicknamed "Monkey Boy," his personality closely resembles that of a playful monkey.
He becomes Ran's boyfriend, though she consistently avoids any form of intimacy. This sometimes makes Tatsuki feel uncertain about their relationship, as Ran rarely shows public displays of affection indicating he is her boyfriend. Tatsuki enjoys incorporating English words and phrases into his conversations. He often repeats phrases, switching between English and Japanese. For instance, he might say "Black nichiyōbi," followed by "Black Sunday," and then "Kuroi Sunday." Additionally, he likes to call Yuya "brother" in English.
