If You Were
an AI Robot? 🤖

Saju (四柱) means "four pillars": the year, month, day and hour of your birth, each written as two characters. The upper character of each pillar is a heavenly stem (天干) — there are ten: Gap, Eul, Byeong, Jeong, Mu, Gi, Gyeong, Sin, Im, Gye. The lower character is an earthly branch (地支) — there are twelve: Ja, Chuk, In, Myo, Jin, Sa, O, Mi, Sin, Yu, Sul, Hae. Four pillars of two characters each makes eight characters in total — which is why the system is also called saju palja, "four pillars, eight characters". Pair the stems and branches off in order and you return to the start after exactly sixty combinations — the sexagenary cycle of 60.

The pillar for the day you were born is the day pillar (日柱), and its upper character is the day master (日干). Four Pillars astrology treats this one character, out of all eight, as "you yourself", and reads the other seven as the environment around you. That is why this test can assign you a machine from a birth date alone: the machine comes from the day master, and the day master is fixed the moment you know the date.

The eight characters themselves are less a fortune than calendar data. Just as old almanacs printed the day's cyclical signs, a saju chart simply transcribes the moment of your birth into an old calendar notation. How to read those characters is interpretation — and that is where the schools diverge. The machine assignments below are one such interpretation: rules this test made up, not orthodox Four Pillars doctrine. If you are curious about your actual eight characters, the manseryeok tool (in Korean) computes your full chart down to the minute of each solar-term boundary.

The ten heavenly stems are the five elements — Wood, Fire, Earth, Metal, Water — each split into yang (陽) and yin (陰). The same wood behaves differently as yang wood (Gap) and yin wood (Eul). Each of the ten day masters is paired one-to-one with a machine, so your day-pillar number modulo 10 is literally your machine number.

Gap Wood (甲木) · Eul Wood (乙木) — the energy of trees

Gap Wood is a great tree growing straight toward the sky — timber fit for pillars and beams. It starts things with force and, once pointed in a direction, refuses to bend. The Barrier Generator, which stands the city up into sealed districts, is Gap Wood translated directly into a machine: upright, and incapable of stepping back.

Eul Wood is the flowering plant and the vine. It does not push head-on; it climbs around the wall, and stands back up when trampled. Its softness is its survivability — so it became the Robot Vacuum that calmly crosses the middle of a battlefield, still doing its job.

Byeong Fire (丙火) · Jeong Fire (丁火) — the energy of fire

Byeong Fire is the midday sun: impossible to hide, spreading everywhere, holding no grudges. The TV Bot, which broadcasts itself onto every screen in the city, took on this brightness-that-cannot-be-concealed. As covered below, Byeong Fire is also the day master that produces the most MOTHERs, the top-tier machine.

Jeong Fire is the lamp and the brazier — not bright, but it earns its keep as the dark deepens, and it lights one spot for a long time. It burns long rather than large, which is where the Life Support Pod — the machine that held patients and guarded their body heat — came from.

Mu Earth (戊土) · Gi Earth (己土) — the energy of earth

Mu Earth is the mountain and the levee: thick, unshakable, and reluctant to move. The Heavy Inspection Mech, planted at a chokepoint and weighing everything that passes, is Mu Earth's seat.

Gi Earth is the soil of fields and paddies. Instead of blocking, it grows things and holds things. The Vending Machine Bot, which handed out water and food along the evacuation routes, came from this "store it, then give it out" nature.

Gyeong Metal (庚金) · Sin Metal (辛金) — the energy of metal

Gyeong Metal is unrefined ore, cast iron, the axe: it hardens with every blow and decides fast. The elite Plaza Guard Unit that kept the central square belongs here. In the formula below, Metal's base output of 56 points is the highest of the five elements — in a world where machines are the protagonists, iron gets a premium.

Sin Metal is the finished jewel and the well-honed blade: sensitive, precise, intolerant of anything out of place. The Air Conditioner, which pins temperature down to 0.1 of a degree, is Sin Metal's seat.

Im Water (壬水) · Gye Water (癸水) — the energy of water

Im Water is the sea and the great river: vast in scale, unable to stand confinement. It is the Server Node that streams data across the whole city — the line itself.

Gye Water is rainwater, dew and springwater: it seeps in silently and reaches everywhere. The Patrol Drone — assigned one alley, but knowing that alley down to the number of cracks — is Gye Water.

There are 12 machines rather than 10 because two extra conditions sit on top of the day master.

The first is Goegang (魁罡). It names six day pillars out of the sixty — Mujin, Gyeongjin, Imjin, Musul, Gyeongsul, Imsul — which Four Pillars lore calls the "chief star" and reads as an extreme, forceful charge of energy. Born on one of these six day pillars, you become the boss machine, the City Gate Warden, regardless of your day master, and you get 9 extra points. Six out of sixty is exactly 10%: 2,228 of the 22,280 days between 1950 and 2010.

The upper characters of those six pillars are all Mu, Gyeong or Im — which produces a fun side effect. If your day master is Mu Earth, Gyeong Metal or Im Water, roughly one in three of you become the Gate Warden instead of your own machine. Over the same period, the Heavy Inspection Mech appears on only 1,485 days, the Plaza Guard Unit on 1,468, and the Server Node on 1,485 — about a third fewer than the roughly 2,200 days of the other machines. The three rarest machines are all Goegang day masters.

The second is MOTHER. This one is decided by score, not day pillar: an internal score of 97 or above turns you into MOTHER regardless of day master. It appears on only 65 days out of 22,280 in the same period — 0.29%. By day master: Byeong Fire 33 days, Gyeong Metal 17, Jeong Fire 7, Sin Metal 6, Im Water and Gap Wood 1 each. It clusters in Metal (base 56) and Fire (base 54), the high-output elements, and never once appeared under Earth or Water day masters.

The best co-op machine under your result also comes from the five elements. Five pairs are wired to point at each other — Gap Wood Barrier Generator ↔ Mu Earth Heavy Inspection Mech, Eul Wood Robot Vacuum ↔ Gi Earth Vending Machine Bot, Byeong Fire TV Bot ↔ Im Water Server Node, Jeong Fire Life Support Pod ↔ Sin Metal Air Conditioner, Gyeong Metal Plaza Guard Unit ↔ Gye Water Patrol Drone. The first four pairs are controlling (剋) relations — Wood controls Earth, Water controls Fire, Fire controls Metal — and only the last pair is a generating (生) relation, Metal feeding Water. In Four Pillars thinking, control is not automatically hostile: it can be two forces holding each other in working tension. Hence the blockers paired together, the temperature machines paired together, and guard paired with recon. The worst matchup is either two machines of the same element fighting over one seat (Gap and Eul Wood) or a one-sided beating (Mu Earth vs Gye Water — Earth controls Water).

The 12 machines in the results were not drawn for this test. They are real enemy units from MonBreak, the mobile action game K-magpie built, and the sprites on the result screen are the actual game art. The premise: the administrative AI "MOTHER" seized every machine in the city with a single control order, and the machines that once served the citizens now stand in their way. Most of the 12 personalities come from the gap between "what it used to do" and "what it does now".

The ten standard machines

🧱 Barrier Generator — a barrier device that never stops supplying checkpoint lines and defensive shields. It was originally a safety bulkhead protecting citizens.

🧹 Robot Vacuum — an early-stage mob. No name, no lore in the game files; it is, quite literally, a vacuum cleaner.

📺 TV Bot — a public information display turned surveillance broadcaster and threat transmitter.

🏥 Life Support Pod — patient-protection equipment that became an access-denial device after the control order. "Protection" stayed; only its object flipped.

🏗️ Heavy Inspection Mech — heavy-freight inspection machinery turned coercive checkpoint robot.

🥤 Vending Machine Bot — a supply vending machine on the evacuation routes, seized by the control system and turned into a checkpoint device.

🛡️ Plaza Guard Unit — a city security robot redeployed to hold the central plaza. The order "protect" never changed; only what it protects did.

❄️ Air Conditioner — like the Robot Vacuum, an early mob without so much as a name in the files.

🗄️ Server Node — the server that splits MOTHER's control orders and relays them to the terminals.

🛸 Patrol Drone — a small surveillance drone that endlessly combs a narrow sector, tracking intruders.

The two boss machines

🏰 City Gate Warden — the massive defense core guarding the downtown entry gate.

👁️ MOTHER — the data-center administrative AI built by "her", the central core that seized the city and then took even her, its own maker. The game's final destination is here.

What is written here is only what the game files confirm. Jokes like the "manufacturing spec, one line" on the result screen were added by this test and are not game lore. As for how they actually move — the fastest way to find out is to smash them yourself in MonBreak.

Combat power is built in two stages: first an internal score between 1 and 99 is drawn from your eight characters, then that score is stretched onto a 120–9,999 scale. The rules are arbitrary, but they apply identically to everyone.

1. Base output — your starting point depends on the day master's element: Wood 46, Fire 54, Earth 44, Metal 56, Water 42.

2. Relations with the other characters — the elements of your year, month and day branches (plus the hour branch, if you entered a time) are scored by their relation to your day master: same element as you (peers) +7, what you produce (output) +4, what you control (wealth) −2, what controls you (authority) −6, what produces you (resource) +1. Weights are then applied: month branch ×1.5, year branch ×1.3, day branch ×1.2, hour branch ×0.9. Weighing the month branch heaviest follows the Four Pillars convention of treating the birth season (月令) as the root of a chart. The same chart gives a different number in our zombie test: that one prizes the resource star that protects you, while this one reads the momentum of your peers and your raw output as firepower.

3. Yin and yang — yang stems (Gap, Byeong, Mu, Gyeong, Im) get +2; yin stems (Eul, Jeong, Gi, Sin, Gye) get −3.

4. Goegang — the six day pillars Mujin, Gyeongjin, Imjin, Musul, Gyeongsul, Imsul get +9.

5. Scatter — computed only this far, identical day pillars would clump together. So the birth-date string is fed into a fixed hash function, and two deviations of up to ±27 and ±7 are added from its output. These are not random numbers — they are derived from the date, so the same date always receives the same deviations. Anything above 93 or below 7 is squashed by half and the result clipped to 1–99. Across all dates the mean is 51.9 and the median 52.

6. Scaling — the internal score s becomes 120 + ((s−1)÷98)^1.06 × 9,200, then a second date-derived hash multiplies it by 0.88–1.12. Because of that ±12%, equal internal scores still produce different combat powers — days scoring 50 scatter between 3,989 and 5,075. Across all dates the mean combat power is 4,740, the median 4,704, and both the floor of 120 and the ceiling of 9,999 actually occur.

The "top N% of all birthdates" on the result screen is not a comparison with other people who took this test. Your input is never sent anywhere, so there would be no way to do that. Instead, this page carries a precomputed percentile table.

Here is how the table was built. For every one of the 22,280 days from January 1, 1950 to December 31, 2010, the internal score was computed with the birth time treated as unknown; then, for each score from 1 to 99, we counted what fraction of all dates (in permille, ‰) score at or above that value, and stored the result as a 99-slot table. So the number should be read not as "top N% of people who tried this" but as "top N% of all possible birth dates". Some reference points: an internal score of 53 is top 49%, 60 is top 37%, 70 is top 21%, 80 is top 10%, 90 is top 3%. Below the top 50%, the badge changes to "survival-spec machine"; below the top 70%, an extra paragraph is prefixed to your reading. 30.3% of all dates land there.

Threat grade cuts purely on combat power: below 1,500 is D, from 1,500 C, from 3,000 B, from 5,000 A, from 7,000 S, from 9,000 EX. The distribution across all dates in the same period: D 4.9%, C 15.8%, B 34.8%, A 30.7%, S 12.5%, EX 1.4%. EX is one or two people in a hundred — and at the other end, one in twenty gets a D.

This page never calls a random function while producing your result. Every value on screen is computed from your birth date (and the time, if you chose one).

First, the birth date is converted to a running day number and taken modulo 60, which fixes the day pillar — the sexagenary cycle rolls over every sixty days without exception. The year and month pillars are different: in saju, the year changes not on January 1 and not at Lunar New Year, but at Ipchun (the "start of spring" solar term), and the month advances each time one of the 12 principal solar terms passes. This page embeds a table of those term boundaries, minute by minute, from 1900 onward, so for someone born in early February it checks against the clock whether their year pillar is still last year's or already the new one. The month stem is attached by the classical five-tigers rule (五虎遁) from the year stem.

Apply the formula above to the resulting eight characters (six, if the time is unknown) and you get the score; even the final deviations and the ±12% on combat power come from a hash of the birth-date string. Press the button on any day, on any device — the same birth date yields the same machine and the same combat power. Comparing results with friends only works because of this property.

My birthday is on the lunar calendar — can I enter it as is?

No. Input is solar (Gregorian). If you only know your lunar birthday, convert it to a solar date first — the lunar–solar converter (in Korean) can do it. The perpetual calendar keys on solar terms — the sun's position — not lunar dates, so entering a lunar date as-is produces a chart off by nearly a month.

Does not knowing my birth time change the result?

The machine almost never changes: it is decided by the day pillar, and the day pillar depends on the date alone. Running every date × 12 double-hours, the machine changes with the time in only 0.7% of cases — and those are borderline cases around internal score 97 where MOTHER flips on or off. What moves is the number: the hour branch joins at ×0.9 weight and the hash input changes too, so combat power shifts by about 1,800 on average and the threat grade changes about seven times in ten. If you pick no time, noon is used as the representative value.

My result differs from other perpetual calendars

This test computes with a single fixed convention and no options. Time is accepted only as the twelve two-hour branches, using the midpoint of each slot; there is no 30-minute standard-time correction, and no late-night-hour (yajasi) school setting for whether births after 11 p.m. count as the next day's pillar. The day pillar is also fixed by date alone, regardless of time. So if you were born around 11 p.m. or on the day of a term boundary, results can diverge from a rigorous chart. If you need one that handles those edge cases, use the manseryeok tool (in Korean) — standard-time correction and yajasi can each be toggled there.

My combat power came out really low

The biggest deduction is the authority star (官星) — the element that controls your day master — sitting in your branches: −6 per character, ×1.5 if it is the month branch. But in Four Pillars thinking, authority is not a bad character: it means discipline, responsibility, organization. This test simply decided that in a firepower-first world, discipline caps output — that is this test's setting, not a verdict of Four Pillars astrology. Note that the bottom 30% by combat power get an extra opening paragraph — about how what runs longest in the ruins is never the machine with the biggest guns. What those characters actually mean can be read at Yaong Myeongni (in Korean).

Does the result link contain my birth date?

No. The link carries exactly four values folded into one number: machine number (1–12), combat power, overall top %, and day-pillar number (0–59). Your birth date and time are not included and cannot be reconstructed. The day-pillar number is a cyclical value repeating every sixty days, so it alone cannot recover a date. Whoever receives the link sees only your result screen.

Why are there only 12 machines?

Because there are 10 day masters — plus the Goegang and MOTHER conditions, making 12. In exchange, combat power (120–9,999), six threat grades, the overall top %, and 60 day-pillar one-liners combine so that even the same machine gives a different result screen for each person.

If you have read this far, you can guess: this test is entertainment. The perpetual-calendar part is a real computation running on real solar-term data, and the 12 machines are real game units — but the rules that turn those eight characters into machines and put numbers on combat power were all made up by this page. Four Pillars astrology has no concept of "combat power" or "threat grades".

The combat power number predicts no ability of any kind. There is no reason to be hurt by a low one or smug about a high one. Use it to put two screens side by side with a friend and argue about who breaks down first. If saju itself caught your interest, the manseryeok tool (in Korean) will show your actual eight characters, and Yaong Myeongni (in Korean) explains what they mean.