Answer
"Osamu," the latter half of Dazai's pen name, carries the profound meaning of "to govern" or "to rule." This selection aligns perfectly with Dazai's literary prowess and the influential impact his writings had on the Japanese literary landscape. His works, often introspective and delving into the depths of human emotions, held a captivating power that resonated with readers, cementing his position as a literary force to be reckoned with.