The eight characters of a Saju chart do not all carry equal weight. Traditional Korean-Chinese astrology singles out one of them — the Heavenly Stem of your birth day — as the axis of interpretation. This character is called the Ilgan (日干), or Day Master. The personality analysis in Hamhee K-SAJU also starts from your Day Master.

Why the Birth Day, of All Things?

Everyone born in the same year shares the same year pillar, and everyone born in the same month shares the month pillar. The day pillar, however, rotates on a sixty-day cycle, making it a far more personal unit. As the discipline of Saju developed over centuries, the position representing "the self" gradually shifted from the year pillar to the day pillar, and modern interpretation almost universally treats the Day Master as the reference point.

Once the Day Master is fixed, the remaining seven characters are all re-read in terms of their relationship to it. Some characters support the Day Master, some are governed by it, and some keep it in check. The naming system for these relationships is called the Ten Gods (Sipsin, 十神).

The Ten Flavors of Day Master

Since the Day Master is one of the ten Heavenly Stems, there are ten broad flavors, each with a traditional metaphor:

• Gap Wood (甲木) — a tall, straight tree. Driven, proactive, and dislikes being bent.
• Eul Wood (乙木) — a vine or flowering plant. Flexible, adaptive, thrives through relationships.
• Byeong Fire (丙火) — the sun. Bright, open, a large presence with direct expression.
• Jeong Fire (丁火) — a candle or hearth. Fine-grained focus and warm attentiveness.
• Mu Earth (戊土) — a great mountain. Steady, hard to shake from its center.
• Gi Earth (己土) — cultivated soil. Practical, meticulous, good at nurturing others.
• Gyeong Metal (庚金) — raw ore and the axe. Strong decisiveness, goal-oriented.
• Sin Metal (辛金) — a jewel or needle. Sharp, refined, with high standards for finish.
• Im Water (壬水) — a great river or the sea. Large in scale, embracing, insightful.
• Gye Water (癸水) — dew and streams. Rich sensitivity and quietly penetrating wisdom.

Of course, this is the simplest possible sketch, looking at the Day Master in isolation. Your actual disposition shifts considerably depending on which season (month branch) you were born into and whether the surrounding characters support or restrain your Day Master.

Strong and Weak Day Masters

The same Gap Wood Day Master becomes a "strong-self" (Singang) chart when born in spring surrounded by Water and Wood, and a "weak-self" (Sinyak) chart when born in autumn under heavy Metal restraint. Strong versus weak is not a matter of better or worse; it is the criterion for judging which energies should be added or drained to restore balance. Finding that balancing point is the search for the Yongsin (用神), which we cover in a separate guide.

Using This on Your Result Page

When you read your analysis, first check which Day Master you have, then compare the sketch above with how you actually are. Some parts will fit and some will not — and the misfits are the interesting part. They may reflect the influence of surrounding characters, or the way environment and effort have reshaped your innate grain. Remember that Saju is not an answer sheet; it is a mirror for self-understanding.