Kairo
Korean Saju
Patterns before predictions
Hidden Stems (지장간): What Sits Inside Each Branch
Each of the twelve Earthly Branches carries one to three Heavenly Stems inside it, and they decide whether a Day Master is rooted and whether a "missing" element is really missing.
Every Earthly Branch (지지, 地支) in a Saju chart contains between one and three Heavenly Stems (천간, 天干). These are the hidden stems (지장간, 支藏干, jijanggan). The last one listed for each branch is the branch's own element, and the others are elements the branch carries from the neighbouring season or from its role as storage. Hidden stems are the layer that decides whether a stem in the chart is rooted and whether an element absent from the visible eight characters is absent at all.
The table
The common Korean table lists the stems of each branch in a fixed order: residual (여기, 餘氣, yeogi), middle (중기, 中氣, junggi) and principal (정기, 正氣, jeonggi), with the principal stem last. Three branches carry a single stem; the other nine carry three.
| Branch | Residual | Middle | Principal | Principal element |
|---|---|---|---|---|
| Ja 子 | Gye 癸 | Water | ||
| Chuk 丑 | Gye 癸 | Sin 辛 | Gi 己 | Earth |
| In 寅 | Mu 戊 | Byeong 丙 | Gap 甲 | Wood |
| Myo 卯 | Eul 乙 | Wood | ||
| Jin 辰 | Eul 乙 | Gye 癸 | Mu 戊 | Earth |
| Sa 巳 | Mu 戊 | Gyeong 庚 | Byeong 丙 | Fire |
| O 午 | Byeong 丙 | Gi 己 | Jeong 丁 | Fire |
| Mi 未 | Jeong 丁 | Eul 乙 | Gi 己 | Earth |
| Sin 申 | Mu 戊 | Im 壬 | Gyeong 庚 | Metal |
| Yu 酉 | Sin 辛 | Metal | ||
| Sul 戌 | Sin 辛 | Jeong 丁 | Mu 戊 | Earth |
| Hae 亥 | Mu 戊 | Gap 甲 | Im 壬 | Water |
The principal stem is what the branch "is". Myo 卯 is Wood because its only stem is Eul 乙; O 午 is Fire because its principal stem is Jeong 丁.
Note the polarity pattern. Ja 子 and O 午 are yang branches whose principal stems, Gye 癸 and Jeong 丁, are yin. Sa 巳 and Hae 亥 are yin branches with yang principals, Byeong 丙 and Im 壬. The four are the middle of each season, and the mismatch is a feature of the table.
Why the storage branches hold three stems
Jin 辰, Sul 戌, Chuk 丑 and Mi 未 are the four Earth branches, one at the end of each season. In the month sequence Jin closes spring (April 5 to May 5), Mi closes summer (July 7 to August 7), Sul closes autumn and Chuk closes winter. The tradition calls them storage branches (고, 庫, go), because each one holds the stem of the season that is ending as its residual, and a second stem in its middle position, on top of its own Earth.
Mi 未 shows the logic. Its residual is Jeong 丁, Fire, the season just ending. Its middle is Eul 乙, Wood, which the tradition assigns to Mi as the stored form of the Wood cycle. Its principal is Gi 己, Earth. A birth in the Mi month therefore has Fire, Wood and Earth in its Month Branch before any other character is read.
The four "birth" branches at the start of each season, In 寅, Sa 巳, Sin 申 and Hae 亥, also hold three stems, for a different reason: each carries Mu 戊 Earth as its residual, marking the transition from the storage branch before it. Three of the four middle-of-season branches, Ja 子, Myo 卯 and Yu 酉, hold a single stem. O 午 is the exception, carrying Gi 己 in its middle position between Byeong 丙 and Jeong 丁.
What "rooted" means
A Heavenly Stem on the top row is rooted (통근, 通根, tonggeun) when a branch in the chart contains a hidden stem of the same element. Rooting is how the tradition measures whether a visible stem has support underneath it.
The Day Master's own branch is the first place to look. Take two Eul 乙 Wood Day Masters:
| Birth date (Seoul) | Day Pillar | Hidden stems of the day branch | Eul's root |
|---|---|---|---|
| February 10, 2026 | Eul-Myo 乙卯 | Eul 乙 | Principal stem, own element |
| July 20, 2026 | Eul-Mi 乙未 | Jeong 丁, Eul 乙, Gi 己 | Middle stem, shared with Fire and Earth |
Both are rooted. The February chart sits on a branch whose only content is Eul: the tradition reads that Day Master as standing on solid ground. The July chart sits on a storage branch where Eul is one of three stems and Earth is the principal: the root is real and read as weaker, and the branch also introduces Fire and Earth directly under the Day Master.
A Day Master with no root anywhere in the four branches is read as exposed, and that changes how every other relationship is weighed. This is one of the inputs to the strong-versus-weak judgement (신강, 身强 / 신약, 身弱), along with the season of the Month Branch and the count of Companion and Resource characters.
The "missing element" question, done carefully
Element counters look at the eight visible characters and report what is absent. Hidden stems make that report incomplete.
Take a birth on February 10, 2026 in Seoul, hour unknown. Six characters are known:
| Pillar | Stem | Branch | Hidden stems |
|---|---|---|---|
| Year | Byeong 丙 Fire | O 午 Fire | Byeong 丙, Gi 己, Jeong 丁 |
| Month | Gyeong 庚 Metal | In 寅 Wood | Mu 戊, Byeong 丙, Gap 甲 |
| Day | Eul 乙 Wood | Myo 卯 Wood | Eul 乙 |
On the visible six, Fire, Metal and Wood are present and Earth and Water are absent. In the hidden stems, Earth appears twice: Gi 己 inside O 午 and Mu 戊 inside In 寅. Water appears nowhere. So the careful statement is that this chart has no visible Earth and no Water at all in its six known characters, and that the Hour Pillar, once known, could add either.
The difference matters for how a reading proceeds. An element present only in hidden stems is read as latent, available to be drawn out by a cycle or a combination. An element absent from both layers is read as genuinely outside the chart until a daewoon (대운, 大運) or annual pillar brings it. The site's article on the Five Elements covers what the tradition makes of each case. The count has to be taken on both layers before anything is said about absence.
How schools differ
Some schools go further than the table and assign day-counts to the three positions within the month. In the common version, the In 寅 month spends its first seven days under Mu 戊, the next seven under Byeong 丙 and the remaining sixteen under Gap 甲, so a birth on February 6, 2026, two days after Ipchun, falls in the residual Mu period of the In month.
The tables also vary at the edges. Some versions give Ja 子 a residual Im 壬 alongside Gye 癸, leave Gi 己 out of O 午, or reorder the counts for the storage branches by a day or two. These are differences between texts and teachers, and there is no ruling that settles them. Kairo uses the table given above, without day-counts, and treats the twelve-branch list as fixed for every chart it calculates.
Pattern questions
- Do you know which branch your Day Master sits on, and whether that branch contains your Day Master's element? If not, you do not yet know whether the tradition reads you as rooted.
- Has a reading told you an element is "missing"? Check the hidden stems of all four branches before accepting the count.
- Were you born in a Jin, Sul, Chuk or Mi month? Your Month Branch carries three elements, and a reading that names only Earth has read one of them.
- Have two services given you different element counts from the same birth data? One is probably counting hidden stems and the other is not.
What this can and cannot tell you
The hidden-stem table is fixed, and under Kairo's convention every branch resolves to the same stems in every chart. What follows from it is interpretive. "Rooted" and "latent" are the tradition's terms for structural positions in the chart, and Saju is an interpretive tradition, not a validated predictive method; Kairo does not present it as one. A responsible reading says which layer a claim came from, the visible stem, the principal hidden stem or a residual, and a claim resting on a residual stem carries the least weight.