Chiharu Sakaki is a student at the specialized high school that serves as the primary setting for the anime Opus.COLORs. He is a young man with blonde hair cut to neck length and blue eyes, standing at 178 centimeters tall. His birthday is February 14th, and his blood type is B. Chiharu is a third-year student in the Grader major.

As a Grader, Chiharu's role involves the reception and evaluation of Perception Art, a unique form of artistic expression within the world of the series. What sets him apart is his technical skill; he is a rare type of Grader who creates his own frames to house and store Perception Art. This ability is noteworthy as his craftsmanship is respected and admired even by students who are majoring in the artistic side of the discipline.

Chiharu maintains a constant, pleasant smile, but his personality and philosophy are complex and often antagonistic. He unapologetically views Artists as tools or toys for Graders to use. He openly states his preference for partnering with first-year students, as he believes a tool should be obedient. This superior and dismissive attitude makes him a natural enemy to Kazuya, one of the main Artist characters who resents this dynamic. Chiharu is amused by the tense and complicated relationship between Kazuya and his friend Kyo, and he enjoys provoking or playfully interacting with Kazuya in a way that highlights their opposing viewpoints.

Regarding his personal relationships, Chiharu is not an isolated figure. He has been close friends with two other characters, Kyo and Iori, since their first year at the school. The three are described as intimate bad friends who know each other well. His development throughout the narrative is primarily defined by his unwavering adherence to a traditional, hierarchical view of the Grader-Artist relationship, positioning him as a consistent foil to other characters who seek a more equal partnership.