Gaku Amane is a highly skilled and unpredictable assassin in the manga series 'Sakamoto Days.' As a member of the Order, an elite group of assassins, Gaku is known for his chaotic personality, immense physical strength, and proficiency with weapons. He often acts as an antagonist, creating significant challenges for the protagonist, Sakamoto, and his allies. Gaku's unpredictable nature and relentless pursuit of his goals make him one of the series' most formidable and memorable adversaries.