One major event in Japan’s 16th-century civil war — which is the focus of “Gunshi Kanbei (Strategist Kanbei),” NHK’s current Sunday-night drama series — involves the duplicitous warlord Akechi Mitsuhide.

Probably moved by personal jealousy, Mitsuhide betrayed his lord and ally, Oda Nobunaga, by staging a coup d’etat at the Honnoji Temple in Kyoto, on June 21, 1582, according to the Western calendar. The 48-year-old Oda died during the battle — it’s believed he committed suicide rather than suffer the ignominy of defeat. Mitsuhide then proclaimed himself 将軍 (shōgun, military commander), a position he held for less than two weeks until falling in battle against another warlord, Toyotomi Hideyoshi.

Mitsuhide’s rapid rise and fall spawned the four-character aphorism 三日天下 (mikka tenka, literally three days under heaven), which refers to a short-lived reign or moment of glory that didn’t last.

The account of Oda’s demise is referred to as 本能寺の変 (Honnoji no Hen, Incident at Honno Temple). This particular hen is not to be confused with the one in この辺 (kono hen, around here), but rather the hen in 事変 (jihen, an accident, disaster, uprising or emergency). It should be noted that a jihen is generally considered to be larger or more momentous than a 事件 (jiken, an event, affair, incident, criminal case or scandal).

The basic meaning of the hen in jihen is “change.” But the word sashays through the Japanese language in all sorts of nuanced variations.

I encountered this variation of hen while studying Japanese literature — it appears in the title of the famous novel 地獄変 (“Jigoku–hen, Hell Screen”), by Akutagawa Ryunosuke, serialized in an Osaka newspaper in 1918. The hen in “Jigoku-hen” is an abbreviation for 変相図 (hensō–zu, a pictorial image from Buddhist mythology).

In daily conversation, however, 大変 (taihen, literally “big change”) must be the most common usage. Applied for emphasis, it can be nuanced in different ways. One might say, 「これは大変だ!」 (“Kore wa taihen da!,” “This is a catastrophe!”). Episodes of “Zenigata Heiji,” a long-running TV drama series set in the premodern era, used to lead off with klutzy character Garapachi stumbling onto the set and exclaiming, 「親分、てえへんだ」 (“Oyabun, taihen [expressed here in dialect as ‘teehen’] da!,” “Hey boss, we’ve got trouble!”)

Reverse the pronunciation of taihen to 変態 (hentai) and you’ve got the word for pervert. But if we drop the tai altogether the meaning of hen changes slightly to refer to something abnormal, such as 彼は頭が変だ (kare wa atama ga hen da, he’s not in his right mind). Or 変に思う (hen ni omou, to think it strange). In a similar vein are expressions such as これはちょっと変 (kore wa chotto hen, there’s something wrong with this), or どこか変ですね (dokoka hen desu ne, there’s something funny somewhere).

Other colloquial usages would include 彼は変な男 (kare wa henna otoko, he’s a weirdo). Hen is often interchangeable with its kun-yomi (i.e., a native Japanese reading of a Chinese character) — 変わる (kawaru) — so you could just as easily say 「彼は変わった男」 (“Kare wa kawatta otoko,” “He’s a strange man”).

In 1998, when three senior Diet members — Junichiro Koizumi, Seiroku Kajiyama and Keizo Obuchi — vied to succeed Ryutaro Hashimoto as the next president of the 自民党 (Jimintō, Liberal Democratic Party), they were humorously referred to, respectively, as 変人 (henjin, the weirdo), 軍人 (gunjin, the soldier) — on account of Kajiyama’s service in the military — and 凡人 (bonjin, an ordinary or mediocre person).

Around the late 1990s, これは変だよ (kore wa hen da yo, this doesn’t make sense) became a popular buzz-phrase. Iconoclastic TV personality “Beat” Takeshi even produced a weekly TV program from 1998 to 2002 on TBS and affiliates titled 「ここがヘンだよ日本人」 (“Koko ga Hen da yo Nihonjin,” “This doesn’t make sense, Japanese people!”), featuring a colorful cast of foreigners from far-flung and nearby nations. The manic style of that TV show reminds me of another hen phrase, 臨機応変の対応 (rinki ōhen no taiō, literally “expedient response”), which means to ad-lib or play it by ear.

When a foreigner became extremely adept at the Japanese language or acquired expertise on some aspect of Japan, they might be humorously referred to as 変な外人 (henna gaijin, a weird foreigner). This term, for better or worse, has fallen into disuse due to political correctness. It was usually applied as うわべだけのお世辞 (uwabe dake no oseji, a left-handed compliment) rather than being regarded as malicious.

Finally we come to 豹変 (hyōhen, literally “leopard change”) referring to a complete about-face in relation to a stance or opinion．A passage in the Bible (Jeremiah 13:23) contains the rhetorical question, “Can the Ethiopian change his skin, or the leopard his spots?” But the Asian usage is much older, perhaps by the order of two millennia. It appears in the 易経 (I Ching/Yijing, The Book of Changes), the ancient Chinese work on divination, as 君子豹変、小人革面 (kunshi hyōhen, shōjin kakumen, wise men change swiftly, small men change only the surface).

Isn’t it remarkable, though, that people so long ago, and in lands so far apart, made a similar association between leopards and change?