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Saju, bazi, shichu-suimei —
one skeleton, three sets of customs

Basics · September 2026 · 7 min read

Are saju, bazi and shichu-suimei different systems?

The names differ, so they look like three separate disciplines. The starting point is one. Write the year, month, day and hour of a birth as a pair of a heavenly stem and an earthly branch each, and you get four pillars and eight characters. Chinese practice names the eight characters directly — bazi, eight characters. Japanese practice names the four pillars — shichu-suimei, divining by four pillars. Korean uses saju (four pillars) and saju-palja (four pillars, eight characters) side by side.

So asking which country got it right does not quite work. When the three traditions disagree, it is almost never the arithmetic — it is the point where a custom forked.

What do all three actually share?

Four pillars, five elements, the ten gods, and a calendar cut by solar terms — these four are identical across all three. Up to here you only need to swap the vocabulary.

• Stems and branches (干支) — ten stems paired with twelve branches, cycling through sixty. The same cycle labels years, months, days and hours.
• Four pillars, eight characters — year, month, day and hour pillar. Reading the day pillar as the self, the Ziping method, is common to all three.
• Five elements and ten gods — wood, fire, earth, metal and water, plus the ten relationships between the day stem and every other character. Japanese sources call the ten gods tsuhensei (通変星); the framework underneath is the same.
• Solar terms — the year turns at Ipchun (입춘, 立春) in early February, not on 1 January, and the month turns at a solar term rather than on the first of the month. All three agree.

The classics are shared too. The Ziping texts were written in China, and Korea and Japan each shaped what they received. These are three branches, not three trees. Even shinsal markers like yeokma, the traveling horse, appear in all three under different spellings.

So where exactly do they split?

The clock matters because anyone born near a two-hour boundary gets a completely different hour pillar depending on whether the correction is applied. Near the boundary of the Rat hour it can move the day pillar as well, which is where the schools that treat late and early Rat hour differently come from. City-by-city corrections are laid out in birth time correction.

The top three rows are effectively identical. The bottom four are where real difference lives, and the last two rows are not theory at all — they are local custom.

What is the same idea called in each language?

Vocabulary is the usual source of confusion. With the mapping in hand you can read sources from all three traditions together.

The one that trips people up is tsuhensei. When a Japanese source says tsuhensei, it means the same thing Korean sources call sipsin and Chinese sources call shishen — the ten gods. Different spelling, same machinery.

Which customs are specifically Korean?

Son-eomneun-nal, Tojeong-bigyeol, and a date-picking habit that runs through ordinary life — those three mark the Korean side.

• Son-eomneun-nal (손 없는 날) — days whose lunar date ends in 9 or 0. The son is a spirit thought to move around the compass with the date, so these are the days it is absent. Plenty of people still book a move or a shop opening this way.
• Tojeong-bigyeol (토정비결) — a book for reading the coming year, used since the late Joseon period and still consulted around Lunar New Year. It does not build a full chart; it reads one year, briefly.
• Gunghap and date-picking — choosing a wedding, a move or an opening by chart is unremarkable in Korea. Travel dates get the same treatment, as in picking a good day to travel.
• Manseryeok — the name of the table you look pillars up in. Where a Chinese almanac also tells you what today suits, the manseryeok is closer to a pure lookup table for pillars and solar terms.

How do the Japanese and Chinese customs compare?

They ask different questions, so there is nothing to rank.

Japanese kyusei-kigaku (九星気学) works from a single honmeisei, a star fixed by birth year and month, and reads directions from it. Saju builds all eight characters from year, month, day and hour, and direction is derived from part of that. Different starting points give different kinds of answers: kyusei-kigaku asks which direction to treat carefully this year, saju asks what mixture a person is made of.

The Chinese almanac (農民曆 / 黄历) lists yi and ji — suitable and unsuitable — line by line for each date, activity by activity. The Korean son-eomneun-nal did not come from there. It follows a far simpler rule, the last digit of the lunar date, and is used mainly for moves and openings. Both are date-picking, but the roots differ, which is why the two can disagree about the same day without either being wrong.

Which tradition should I read my chart in?

Whichever you already know — just set the clock to where you were born. The rules for building the eight characters are the same either way, so a chart cast in Korean manseryeok style gives the same characters whether you were born in Singapore or Osaka. The hour pillar is the only piece that moves, so the longitude correction for your birth city is the one thing worth getting right.

For travel, this order keeps things simple.

• Correct the birth time firstCorrections differ by city, and everything downstream inherits the error if this is off.
• Read in the vocabulary you knowLearned it as bazi, read it as bazi. Keep the mapping table beside you and nothing is lost.
• Follow local custom for datesBooking a move or an opening in Korea, use son-eomneun-nal. For the rest, see fortune-telling culture in Korea.

5htrip builds your chart with the longitude correction for your birth city applied, and gives you the day pillar each morning in five languages. It runs on a verified Manseryeok engine, so it is free every day.