straw bag, (kokuji)
叺 centers on a straw bag, specifically a type of woven straw sack. It is a kokuji, a kanji created in Japan, so its meaning is tied to this specific object.
叺 is a kokuji (Japanese-made kanji) combining 口 (mouth/opening) and 入 (enter), likely representing the idea of something entering an opening, i.e., a bag. The exact historical development is uncertain.
The left side 口 is an opening, and the right side 入 means enter. Picture stuffing straw into an opening to make a straw bag.
For かます, imagine a straw bag filled with 鎌 (かま, sickle) and 酢 (す, vinegar): かま + す -> かます. The bag holds the sickle and vinegar.
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