Rei is The Ocean Rat

This is the day pillar only. It is fixed by the calendar date of birth, which is public — so it can be calculated with confidence. The hour pillar cannot: Rei's birth time is not published, and guessing at one would produce a chart that looks precise and is not.

What the day pillar says is character rather than circumstance. The Ocean Rat is the Ocean — yang Water — standing on the Rat.