Short answer: In Korean Saju (the Four Pillars of Destiny), the Day Master (일간, 日干) is the Heavenly Stem of the day you were born. It is the one character in the chart that represents you; every other character is read by how it relates to it.
Where the Day Master sits
A Saju chart has four pillars — year, month, day and hour of birth. Each pillar has a top character (Heavenly Stem) and a bottom character (Earthly Branch). The top character of the day pillar is the Day Master.
The 10 possible Day Masters
There are ten Heavenly Stems, so there are ten possible Day Masters. Each one combines one of the Five Elements with Yin or Yang:
- Wood: Gap (甲, Yang) · Eul (乙, Yin)
- Fire: Byeong (丙, Yang) · Jeong (丁, Yin)
- Earth: Mu (戊, Yang) · Gi (己, Yin)
- Metal: Gyeong (庚, Yang) · Sin (辛, Yin)
- Water: Im (壬, Yang) · Gye (癸, Yin)
Why it matters
Readers use the Day Master as the reference point. The other seven characters are described by their relationship to it — supporting it, draining it, controlling it and so on (the "Ten Gods" system). That is why two people born in the same year can get very different readings.
Do I need my birth time?
No — the Day Master comes from your birth date. (Births close to midnight can be counted differently by different schools, so the exact time still helps.) The hour pillar, however, does need the birth time.
See yours
You can see your own Day Master and full chart for free by entering your date of birth on bujasaju.net. The chart is calculated from your details — nothing is guessed.
Frequently asked questions
Q. Is the Day Master the same as my zodiac animal?
No. Your zodiac animal comes from the year pillar's Earthly Branch; the Day Master comes from the day pillar's Heavenly Stem.
Q. Is one Day Master better than another?
No. Each has its own character; Saju reads balance in the whole chart, not a ranking.
Q. Can my Day Master change?
No. It is fixed by your birth date. Yearly and 10-year cycles are read against it.