How BaZi Traveled: Four Names, One Calculation

The same eight characters are computed the same way in four countries. There is no national variant of the machinery — no Korean stem order, no Japanese month boundary, no Vietnamese sixty-term cycle — so one birth moment resolves to one set of pillars whichever country's calculator you hand it to. A chart cast in Seoul and a chart cast in Taipei agree.

What varies is everything around the computation. Each country received the system at a different moment, gave it a different name, and — most consequentially — put it in a different place.

Four names

Three of the four are the same compound — 四柱, four pillars — read in three languages. China's everyday word is the other one, 八字, though 子平 and 命理 are also standard there.

The Japanese name is the odd one, and it is odd in a specific way.

Japan named it itself

四柱推命 does not appear in the Chinese source texts. It is a Japanese coinage.

Chinese practice calls the system 子平, 命學, 命理 or 八字. Nobody in China called it 四柱推命 before Japan did, and the term did not travel back. So while Korea and Vietnam took the Chinese compound and read it locally, Japan built a new name — 四柱 plus 推命, "inferring fate."

The coinage has an attributed origin. Sakurada Tōgen 桜田虎門 (1774–1839), a Confucian scholar teaching at the Sendai domain's academy, produced the 推命書 — a translation and adaptation of the Yuanhai Ziping. Dates vary by source: some give an initial version around 1801, with the better-known reissue in 1818, and a supplementary printing in 1831.

That is late. The Yuanhai Ziping had reached its circulating form in 1634, and Japan's translation followed roughly two centuries after that. By then Korea had been examining candidates on a Song Four Pillars text since 1466 — for over three hundred years.

Japanese sources also note that Sakurada was a Confucian scholar rather than a specialist in the material, and question the translation's quality on that basis.

The confusion worth clearing

Search for Japanese divination in English and you will meet Abe no Seimei 安倍晴明 (921–1005) — court diviner, subject of novels, manga and films, the most famous name in the field.

He has nothing to do with shichū suimei.

Abe no Seimei belonged to 陰陽道 Onmyōdō, the "way of yin and yang," practised through the Onmyōryō — a bureau of the ritsuryō state. Onmyōdō did calendar-making, astronomy and astrology, and a divination form called 六壬式占, worked with a divining board. Not four-pillar fate calculation.

And Onmyōdō is not a Chinese import under a Japanese name. The scholar Masuo Shin'ichirō puts it flatly: the term Onmyōdō cannot be found in China or Korea. It is a religion that came into existence only within Japan, assembling Chinese folk religion, Daoism and esoteric Buddhism into something with no continental equivalent.

So: two traditions, both Japanese, both built from Chinese materials, separated by about eight hundred years. Onmyōdō was a state bureau in the Heian period. Shichū suimei arrived in the late Edo period as a translated book.

The conflation is mostly the fault of popular culture — the Onmyōji novels and films of the 1980s onward made Abe no Seimei a household name, and English-language writing has tended to fold everything Japanese and divinatory under him since.

What Japan did with it afterwards

Having received the system late, Japan then diverged from it deliberately.

The modern practical form is largely Abe Taizan's, established in the Shōwa period from the Qiong Tong Bao Jian, the Di Tian Sui and the writings of the late-Qing author Xu Lewu. A competing line runs through Takagi Jō.

And there was an explicit programme behind this. A study of early-Shōwa shichū suimei texts describes Japanese practitioners working to divest from Chinese ideological traditions in favour of schools of thought distinctively Japanese — debating predestination, the place of religion in modernity, and accessibility, as part of localising an originally Chinese art.

That is a different relationship to the source than Korea's. Korea examined candidates on the Chinese texts for four centuries and produced its own canon much later; Japan received the texts late and set about making them Japanese almost immediately.

One practical consequence you will meet: Japanese practice readily reads 三柱推命, three pillars, when the birth hour is unknown. The term exists as a normal variant in a way it does not elsewhere.

Korea, briefly

Covered at length elsewhere, but the contrast is the point.

Korea received the system in the thirteenth and fourteenth centuries — attached to Neo-Confucianism, arriving from the Yuan — and put it inside the state. A division of the Bureau of Astronomy, a set text fixed in law in 1466, a graded examination with a quota, for roughly four hundred years.

No other country in this list did that. China had state astronomical offices, but fate calculation was practised outside them. Japan's Onmyōryō was a state bureau, but it did not do this.

That institutional difference is most of why Saju is ordinary in Korean life and BaZi is exotic in English.

Vietnam, and an honest gap

Vietnamese practice exists, shares the Sinitic transmission, and is called Tứ Trụ — the Vietnamese reading of 四柱 — or bát tự. Both it and the Japanese case appear more briefly in the argument that Saju and BaZi are one system.

Beyond that I could not find rigorous sourcing. English-language searching is actively unhelpful here, because "tứ trụ" in modern Vietnamese usually refers to the four senior posts of the Communist Party leadership rather than to anything divinatory.

So this section is shorter than it should be, and that is a gap rather than a finding. If you know the Vietnamese-language scholarship, it is the part of this post most likely to be wrong by omission.

What actually differs in practice

Very little, and it is worth being precise about how little.

The computation is identical. Same stems, same branches, same hidden stems, same Ten Gods, same luck pillars. A Korean 만세력 and a Chinese calculator produce the same eight characters.

The terminology is the same characters, differently pronounced. 일간 is 日干. 신강신약 is 身強身弱. 용신 is 用神. Not translations — the same words.

The textual leanings differ. Chinese and Korean practice both work from the classical canon. Japanese Taizan-ryū leans particularly on the Qiong Tong Bao Jian and Di Tian Sui through Xu Lewu. Korea developed its own twentieth-century didactic canon on top of the classics.

And the boundary conventions can differ, which is the one place a reader will actually notice. Korea names the two halves of the 子 hour explicitly — 야자시 and 조자시 — and argues the distinction. That is one of the genuine forks that makes two correct calculators disagree.

The calculation travelled intact. Everything else was rebuilt locally — the name, the institution, and in one place the boundary of a single hour.