the hair on the temples
鬂 refers specifically to the hair on the temples, the area just beside the forehead.
鬂 combines 髟 (hair) with 兵, which likely contributes the sound. The character is a phono-semantic compound for hair at the temples.
The top 髟 means hair. The bottom 兵 looks like a soldier. Imagine a soldier's helmet strap pressing against the hair on his temples.
For ヒン, picture a soldier with a thin strap pressing on his temple hair: thin -> ヒン.
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