What is Nine Star Ki?
One star out of nine — and the question of where the year actually begins.
The idea
Nine Star Ki (九星氣學 · 구성기학, kyūsei kigaku) sorts people into nine stars, each carrying a colour, a five-element value and a compass direction: 一白水星 is water in the north, 二黑土星 is earth in the southwest, on up to 九紫火星, fire in the south. The star you were born under is your 본명성 — your main star. It belongs to the same family that gave feng shui the Luo Shu magic square, which is why the nine numbers sit in that familiar three-by-three pattern.
How Bokki calculates it
Take the birth year, add its digits down to a single digit, then subtract that from eleven; if you land on ten, wrap it back to one. 1994 goes 1+9+9+4 = 23 → 2+3 = 5 → 11 − 5 = 6 → 六白金星, metal, northwest. That is the whole formula, and it is the mainstream 園田 lineage version — sum every digit, eleven minus, wrap. We checked it against a published year table for sixteen years, including the 1999→2000 century roll, and it matched sixteen out of sixteen.
Where the year begins, and why that matters more than the formula
The Nine Star year turns at 立春, around 4 February — not on 1 January. Someone born on 20 January belongs to the previous year's star, and getting that wrong hands a whole cohort of people the wrong answer. Bokki reads the actual solar term rather than assuming a date, because 立春 is a moment and not a day: in 2025 it fell on 3 February at 22:10, in 2018 on 4 February at 05:28 — the almanac's UTC+8 clock, an hour behind Korea's. A birthday given without a time is read as midnight, so a birth on the morning of 立春 day is still before it — which is exactly the rule our Saju year pillar uses. That sameness is deliberate. The two calculations look at the same instant, so one person can never receive one year from their Saju and a different year from their star. It used to be possible, and a test now holds the agreement in place.
What Bokki does not calculate
Only the 본명성. The monthly star (月命星) and the daily star (日命星) are not computed, and neither are the 年盤 and 月盤 — the rotating boards a practitioner lays over the compass to judge a direction for a particular month or year. Which means Bokki does not do 吉方位取り, the practice of choosing where to travel by the board. And one thing is missing on purpose rather than for want of a table: 方位殺, the unlucky-direction warnings. We do not publish those. Telling someone that a direction will harm them is fear, and fear is the one thing we have promised never to sell.
Where you meet it
Your 본명성 appears inside your daily reading, in the row of other mirrors below the main text, with one warm line for the star. It sits next to your Saju day-master and your feng shui direction — three traditions describing the same person from three angles, which is more or less the whole idea here.
Closing note — the boundary was the real work
To sum up: the main star is a two-line formula, but the year boundary is the moment of 立春. Bokki reads that boundary from the same solar-term calculation as the Saju year pillar, and one test keeps the two traditions in agreement.
Building it, the hard part was the boundary, not the formula. At first the Saju and Nine Star Ki calculations watched different boundaries, so the same person could receive different years from the two screens; merging them onto one solar-term module is what made that mismatch structurally impossible. Only then did we run the sixteen-year check against a published table — verify the ruler first, then trust it. Section 3 above is that decision written down.