zebra with yellow eyes and red mane
馼 refers to a specific mythical or rare zebra-like creature with yellow eyes and a red mane. Its meaning is narrow and descriptive rather than conceptual.
馼 combines 馬 (horse) with 文 (pattern, writing), likely to describe a horse-like animal with distinctive markings. The exact historical origin is uncertain, but it is a phono-semantic compound where 文 may hint at the sound and the patterned appearance.
A horse (馬) with a pattern (文) of yellow eyes and a red mane: 馼 is that uniquely marked zebra-like creature.
For ブン, imagine a bun-shaped marking on the zebra's red mane: bun -> ブン, and the patterned horse shows off its bun-like spot.
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