中身
なかみ · nakami · JLPT N3 · noun
content
📦 中身 = inside (中) + body (身): the body of what's inside
身 can mean flesh, the meat inside a shell. 中 means inside. So 中身 is the flesh inside the shell: the contents of a box or bag, or the substance of an argument, as opposed to its packaging.
中 — vertical stroke 丨 through enclosure 口
Pictograph of a banner or pole piercing the center of a target or territory, depicting the idea of 'middle' or 'center'. The horizontal frame represents boundaries, and the vertical line marks the central axis. The meaning extended from spatial center to 'middle, central, China' (中国, the Middle Kingdom).
身 — pictograph of a pregnant body
身 is a pictograph originally depicting a person with a swollen belly, representing a pregnant woman in profile. Over time the meaning broadened from 'pregnancy' or 'torso' to refer to the body in general, and by extension oneself or one's person.