anxiety, mercy
憫 centers on a troubled heart that reaches out to suffering: feeling anxiety about distress and responding with mercy or compassion.
憫 combines the heart radical 忄 with 閔, which likely contributes the sound and carries a sense of grief or concern. The exact historical development of 閔 is uncertain.
The heart 忄 beside 閔 suggests a heart weighed down by a heavy gate of worry. When that gate opens, mercy flows out toward those in distress.
For ビン, picture a bin of anxious letters under the gate: each letter is a plea for mercy, and the bin (ビン) overflows with compassion.