Chikusa Kakimoto, often called Chiku by his close associates, is a character whose quiet exterior belies a deadly proficiency and unwavering loyalty. His appearance is distinctive and immediately recognizable. He is a tall, slender teenager who typically wears the green uniform of Kokuyo Junior High School. His most notable features include a pair of glasses, a white beanie-style hat, and a barcode tattooed on his left cheek, with a bandage often seen on his right cheek. This combination of school attire and unusual markings gives him a peculiar presence that is both ordinary and threatening.

His background is rooted in tragedy and violence. Chikusa was born into the Estraneo Famiglia, a mafia family that was persecuted for developing and using a forbidden weapon known as the Possession Bullet. As a child, he, along with his friend Ken Joshima and a boy named Mukuro Rokudo, was subjected to horrific experiments by the family. This brutal childhood was the defining experience of his early life. The torment they endured came to an end when Mukuro used his powers to annihilate the entire Estraneo Famiglia, liberating Chikusa and Ken from their suffering. From that moment on, Chikusa swore absolute loyalty to Mukuro, dedicating his life to the one person who had saved him from a living hell. This past left permanent marks on him, not just the physical barcode on his face, but also a deep-seated understanding of the mafia's cruelty and a willingness to do whatever is necessary to survive and serve his master.

The core of Chikusa's personality is his profound silence and stoicism. Unlike his loud and brash partner, Ken, Chikusa rarely speaks, choosing his words carefully and only when necessary. He often gives the impression of being apathetic or simply tired, and his frequent muttered complaint is "Mendoi," which means "troublesome". He is, by far, the calmest and most level-headed of Mukuro's subordinates, a trait that becomes the group's voice of reason. Despite his reserved nature, he is not without emotion. He frequently bickers with Ken, often in a quiet, sarcastic manner that needles his more hot-headed partner. He also cares deeply for his comrades, though he never expresses this openly, especially regarding Chrome Dokuro, whose well-being he monitors with concealed concern.

Chikusa's role in the story is primarily that of a dedicated and highly capable subordinate. As a member of the Kokuyo Junior High Gang, he is one of Mukuro's primary agents, tasked with carrying out his plans to take control of the Vongola family's young heir, Tsuna Sawada. During the Kokuyo Arc, he is a formidable antagonist, demonstrating his skills as a professional assassin. Even after his defeat and subsequent arrest by the Vindice prison guards, his loyalty does not waver. He remains a key supporting figure, helping to protect and support Chrome, who serves as Mukuro's connection to the physical world. In the Future Arc, his role expands as he is shown to have grown stronger, now wielding weapons infused with Rain Flames, which complement his tranquil nature and ability to immobilize opponents. Throughout these later conflicts, his primary motivation remains unchanged: to free Mukuro from his imprisonment and serve his will without question.

His relationships are intense and define his character. His bond with Ken Joshima is that of bickering brothers and lifelong partners. Ken constantly mocks him with nicknames like "four-eyed kappa" or "Kakipi," to which Chikusa usually responds with sarcastic remarks or by tattling on Ken to Mukuro. Despite their constant arguments, they are a perfectly coordinated team in battle and share an unbreakable trust forged in their traumatic childhood. His devotion to Mukuro Rokudo is absolute. He views Mukuro as his savior and follows him with a fanatical dedication, even stating that he does not mind if Mukuro is simply using him as a tool. He is willing to sacrifice his own life and never wavers in his mission to see him freed. With Chrome Dokuro, Chikusa shows a more subtle, caring side. While he never openly expresses affection, he is quick to intervene when Ken yells at her and is perceptive to her emotional state, showing a protective instinct he rarely displays elsewhere.

Over the course of the narrative, Chikusa sees some development from a straightforward villain to a more sympathetic anti-hero. While his personality remains consistently stoic, his role evolves from an active antagonist to a protective guardian for Chrome and a steadfast member of Mukuro's inner circle fighting alongside the protagonists against greater threats. His development is less about a change in personality and more about the deepening of his established traits, showing that even a quiet, seemingly cold individual can be capable of deep loyalty and hidden warmth.

Chikusa's most notable ability lies in his unique choice of weapon: a pair of red, butterfly-shaped yo-yos known as the "Hedgehog". These are not toys but deadly long-range assassination tools. He is an expert at controlling them with high speed and precision, using them to slash at opponents from a distance. The true danger, however, comes from the inside of the yo-yos, which are capable of releasing a "Needle Shower," a spray of countless poisoned needles that can rain down on an enemy and make escape nearly impossible. His skill with these weapons is so refined that he can fight effectively with one in each hand. In the Future Arc, his abilities are further enhanced when he is shown possessing a Rain-attribute Ring, allowing him to coat his needles in Rain Flames. This addition makes his attacks even more potent, as the Rain Flame's property of tranquility can further slow or immobilize whoever is struck.