Several parts combine into one character.

間 shows the sun (日) shining through a gate (門) — the gap between two closed door-leaves where light leaks in, that "interval, space." It was originally 門 + 月 (moon), moonlight through the gate-crack (閒); later the moon became 日 to give 間.

The simplified form is 间, keeping the inner 日 but reducing 門 to 门 — the form splits by mode.

Korean hanja-sound "gan": 時間 (sigan, time), 空間 (gonggan, space), 間隔 (gangyeok, interval), 人間 (in-gan, human being), 中間 (junggan, middle). That "the space between people" is precisely 人間 (human being) reveals an East Asian view of personhood.

Mandarin: jiān, 1st tone (space) / jiàn, 4th tone (gap, to sow discord). 中间 (zhōngjiān, middle), 房间 (fángjiān, room), 时间 (shíjiān, time), 之间 (zhījiān, between). A one-character, two-tone case — 离间 (líjiàn, to drive a wedge) is 4th tone.

Japanese: on-readings カン (kan) and ケン (ken), kun あいだ (aida) and ま (ma). 時間 (jikan, time), 人間 (ningen, human), 間 (aida, interval), 世間 (seken, society / the world), 居間 (ima, living room). In Japanese architecture 一間 (ikken) is also a unit for measuring tatami rooms.

Memory aid: sunlight (日) through a gate (門) — the empty space between two door-leaves.