narrow-minded
惼 centers on a narrow, restricted mindset: being narrow-minded or intolerant of broader views.
惼 combines 忄 (heart/mind) with 扁, which likely contributes the sound and the idea of flatness or narrowness, together suggesting a narrow mind.
The heart radical 忄 beside 扁, which resembles a flat, narrow signboard, suggests a heart squeezed into a narrow space — a narrow-minded attitude.
For ヘン, imagine a narrow-minded person named Hen who refuses to listen: Hen -> ヘン, and his heart 忄 is as narrow as the flat board 扁 beside it.