Go Mutoh is a 10-year-old Japanese-Filipino boy, the younger son of Koichiro and Mari Mutoh, sporting brown hair and dark skin reflective of his mixed heritage. An avid online gamer interacting frequently with international players, he occasionally uses English phrases in conversation. This habit causes friction with others who view it as un-Japanese, fueling his expressed desire to relocate to Estonia for its advanced technology and esports opportunities.

He typically carries a portable gaming console in a worn fanny pack, a habit that proves critical when an arrow strikes the pack during an escape, saving him from injury. His gaming skills and technological familiarity later aid the group's survival. Go exhibits a strong aversion to vegetables, noted by his family, and often relies on his father for meals like home-packed bento boxes.

Following the initial earthquakes, Go sustains a facial injury near his eye treated by his father with makeshift staples; Go later commemorates the injury with a brow piercing in the same location. Throughout the disaster, he demonstrates resilience alongside his sister Ayumu, though he struggles with survivor's guilt and processes grief differently, particularly after their father's death. His bond with Ayumu strengthens during their isolation adrift at sea, where they share conversations about survival and family memories.

Go develops from a carefree gamer into a more contemplative survivor. He retains his technological interests but shows increased maturity by the story's conclusion, symbolizing adaptation and continuity amid loss.