鞄 is a phonetic-semantic compound: 革 (leather / hide) + 包 (bāo, "to wrap"). The composite literally means "something made by wrapping leather" — a leather bag. The character is one of the most asymmetrically distributed across CJK: nearly extinct in Korean and Chinese, but the everyday word for "bag" in Japanese.

This is a striking case of one CJK language adopting a character into daily life while the others let it fade. Korean and Chinese both express "bag" using other characters (包 bāo, 袋 dài, 背包 bēibāo), leaving 鞄 as a curiosity. Japanese, by contrast, embraced 鞄 and made it the standard word for any kind of bag — schoolbag, briefcase, handbag, traveling case. The Japanese reading かばん (kaban) sounds like a foreign loanword and many Japanese speakers assume it is one, but it actually derives from a Chinese reading of 鞄 (the older Chinese reading was something like *pào → kaban via Japanese phonological adaptation).

Korean reading "po" (when read at all). Effectively absent from modern Korean — bag is rendered in pure hangeul as (gabang) or with the Sino-Korean 包 (po) in compounds like 책가방 / 가방. The reading "po" exists in Korean for several unrelated characters: 包 (wrap), 浦 (port), 捕 (capture), 砲 (cannon) — each etymologically distinct from 鞄.

Mandarin páo, 2nd tone — extremely rare in modern Chinese. Mandarin uses 包 (bāo) for "bag / package," 袋 (dài) for "sack," 背包 (bēibāo) for "backpack," 钱包 (qiánbāo) for "wallet." 鞄 might appear in classical or specialty contexts but never in daily speech.

Japanese on-reading ホウ (hō) is rare. The kun-reading かばん (kaban) is what matters — 鞄 (kaban, bag), 学生鞄 (gakuseikaban, school bag — the boxy traditional Japanese student satchel), 手提鞄 (tesagekaban, "hand-held bag" = handbag), 革鞄 (kawakaban, leather bag — somewhat redundant since 鞄 already means leather bag). For Japanese language learners, kaban is one of the very first nouns introduced, and seeing the kanji 鞄 once you've learned the kana is a small revelation: the character literally means what it sounds like.

Memory aid: leather (革) wrapping (包) — what you carry your stuff in. Used as everyday vocabulary only in Japan.