i know mine only because it was required for an accurate astrological birth chart..
shut up.

it's interesting to look up sometimes! i also know i was born on a Thursday, i don't remember how i know that though..
i believe Bryan knew his birth time just from his family telling him. maybe not down to the minute, but the time of day/hour of the day. so perhaps not super unusual know what time you're born, it's written on your birth certificate after all.
somehow i'm not surprised Eripon would know this.. what surprises me more is that she'll be so up front (no pun intended) about that with Gaki.
