Seimei handan is a Japanese fortune telling system used to determine whether a name’s written form is lucky or unlucky.
A single Japanese name can normally be written many different ways, so the idea is that seimei handan will tell you which of these written forms is the most auspicious. This process involves counting the number of strokes in each kanji character.
Though I’m not sure how widely it’s used among expectant Japanese parents, seimei handan seems pretty popular online. A number of Japanese sites offer free seimei handan readings, and there’s even a seimei handan PlayStation game.