Kubota holds the position of intelligence officer within the Japanese Ground Self-Defense Force (JGSDF). He maintains a professional relationship with Daisuke Aramaki, stemming from their prior collaboration. Kubota's narrative role centers on supplying Aramaki with classified information obtained from the highest levels of the Japanese government, making him a recurring source of critical intelligence for Aramaki's operations.

The surname "Kubota" carries the characters "久" (ku), meaning "long time"; "保" (ho/bo), meaning "protect, guarantee, maintain"; and "田" (ta), meaning "field" or "rice paddy."