This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 伂 is uncertain. It visually combines 亻 (person) with 巿, but the original semantic or phonetic role of these components is unclear.
Since the meaning is unclear, picture a person (亻) holding a cloth (巿) as a makeshift flag, but remember this is just a visual placeholder.
For ハイ, imagine a person (亻) waving a cloth (巿) and shouting 'Hi!' to get attention: Hi -> ハイ.
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