Najimu Mujina is a five-year-old girl serving as president of Mujina Company. Despite her youth and ordinary intellect, she occupies a corporate leadership role. She navigates adult professional responsibilities—handling contracts, addressing customer complaints, managing overtime work, and participating in interviews—while approaching them with a childlike perspective. Her daily routine includes arriving at work in the morning, engaging in play activities, and leaving on time, though she occasionally completes assignments.

She explores diverse business operations such as corporate cleaning, mitigating bankruptcy risks, and overseeing television commercial shoots. Her experiences extend to everyday scenarios like running errands, exchanging presents, and participating in kidnapping-related incidents, all contextualized within her corporate duties. She interacts with employees including a highly capable but overly indulgent secretary, an office clerk of unspecified nationality, and a straight-man role colleague who responds to her unconventional behavior.