Noboru Maeda, nicknamed "Turtle" or "Suppon" for his biting attacks, bore the scars of Hiroshima's atomic bombing as a sixteen-year-old orphan. This trauma left distinctive 10-yen coin-sized bald spots on his scalp. His olive-colored eyes and reddish-brown hair framed a notably short stature, making him the smallest in his group.

Before incarceration at Shōnan Special Reformatory, Maeda survived a decade alone after his family's annihilation, turning to theft, fraud, embezzlement, dine-and-dash, and other uninvestigated crimes. As a child, he often fled home to protect his younger sister from volatile parents, yet inadvertently left her behind on the bombing day—a burden that would haunt him and forge a deep aversion to images of happy families.

Lacking physical strength or combat skills, Maeda relied on cunning and powerful jaws for defense. Initially struggling to connect with fellow inmates in Cell 6 of Block 2, he gradually forged strong bonds, particularly with Ryuuji Nomoto (Scam) and Mansaku Matsuura (Cabbage). His resourcefulness shone through smuggling food for cellmates, demonstrating loyalty. He endured brutal beatings from guard Ishihara, frequently incurred while defending others or breaking rules. This resilience and shrewdness cemented his vital role within the group—a newfound family.

Post-release, Maeda leveraged innate business acumen, thriving in black-market ventures like selling cigars near U.S. Army installations. He founded Maeda Finance, a moneylending operation amassing significant wealth that enabled him to support former inmates financially. His entrepreneurial drive led to near-millionaire status, ownership of two buildings, and steady progress toward substantial wealth, all while maintaining close ties with his cellmates.