Before It Was an App, It Was Already a Letter

I found something today that I didn't know when we named this app.

An old kind of letter

In traditional Korean weddings, before two families agreed to anything, the groom's family would send a formal letter to the bride's family — asking, in effect, for her hand. Folded inside that letter was a small document called sajudanja, listing the groom's four pillars: the year, month, day, and hour of his birth.

People just called the whole thing "saju" for short. But it was never only a slip of paper with a birth date on it — it always arrived wrapped inside a letter, written with real care, because it was carrying something important between two families who hadn't met yet.

Some regions even called this ritual "saseong" instead of "saju" — same custom, different name, same idea underneath: your saju doesn't travel alone. It comes with a letter.

So the name isn't new

When I write your letter each morning, I like knowing this isn't the first time someone's saju has arrived folded inside a letter meant to be read carefully, by someone who mattered. We didn't invent that pairing — we just kept it.

Read today's letter

If you haven't yet, try the free demo — see what today's letter, written just for you, sounds like.