About Fourcast

Korean astrology for modern life.

Fourcast is a Saju (Four Pillars of Destiny) reading app that uses your exact birth date and time to reveal the energetic blueprint you were born with. We blend a thousand-year-old Korean astrological tradition with modern AI to deliver personal insights about your personality, relationships, career timing, and wealth cycles.

Fourcast is built and operated by Oh Happy International, LLC, a company focused on making meaningful self-knowledge tools accessible to everyone.

What is Saju?

Saju (사주, "Four Pillars") is a Korean system of astrology derived from Chinese metaphysics. It maps your birth year, month, day, and hour onto a grid of celestial stems and earthly branches — producing a unique chart that describes your elemental nature, your relationships, your timing cycles, and your life's underlying pattern.

Unlike Western sun-sign astrology, Saju uses all four pillars of your birth data to build a layered, individualized reading rather than a generic one.

Our approach

We combine precise astronomical calculations (solar terms, stem-branch systems spanning 1930–2040) with OpenAI's language models to generate reports that read as personal insights, not horoscopes. Every report is generated fresh from your unique chart data.

We are for entertainment purposes only. Our readings are not a substitute for professional medical, financial, legal, or psychological advice.