Derek Watari, known in the original Japanese version as Daiki Watari, is a character who appears in both B-Daman Crossfire and its sequel series B-Daman Fireblast. He is a young B-Shot who was formerly a top competitor in the South Block, where he held the title of Boss of the South. This reputation was built on his skill and his role as a local champion who ruled over that region. His chosen B-Daman is Supreme Tigare, a model noted for its balance of precision shooting and rapid-fire capabilities.

In terms of personality, Derek is characterized by a rough, careless, and troublemaking nature, which aligns with his rebellious image as a former boss. However, this exterior masks a deep-seated sense of loyalty, which is his most defining trait. He displays unwavering devotion to his ally and mentor, Novu Moru, whom he truly respects as the legitimate Boss of the South. Derek consistently refers to Novu as Boss and is always eager to assist him with any task, demonstrating that his previous status as a ruler was a pretense maintained out of respect for Novu’s authority. This loyalty is so profound that it persists even in moments of personal difficulty, such as after Novu abandoned him following a specific battle, Derek continued to call out for his Boss during a tournament instead of focusing on winning points for himself. His personality is further flavored by a love for tigers, which is reflected in his frequent exclamation of the word Tiger when performing actions.

Physically, Derek has a short stature and is depicted as a child with brown hair that reaches his neck and features yellow highlights, often styled so that it curves off to the left. His eyes are red. His attire typically includes a grey hooded sweatshirt with distinctive eye-like designs on the hood, which is a garment also worn by other B-Shots who followed him during his time as the Boss of the South. Underneath the hoodie, he wears a t-shirt featuring a large mouth-like image, paired with black shorts that have yellow spots.

Derek Watari serves as a significant supporting character who transitions from a rival regional power to a steadfast ally. His primary motivation throughout the story is his allegiance to Novu Moru, and his actions are largely driven by a desire to support his friend and follow his leadership. His role highlights themes of redemption and the importance of genuine respect over assumed power. While not a main protagonist, his presence illustrates the complex web of rivalries and alliances within the B-Daman competitive world. His abilities in battle are closely tied to his bond with his B-Daman, Supreme Tigare, which he uses to execute both rapid-fire barrages and precise strikes, a fighting style that reflects his own impulsive yet surprisingly focused nature.