Hatori was born in the year of the dragon.
in the Shoma family they have a festival and the person who was born in that year does a special dance.

Bibliography:
http://www.fanpop.com/spots/funkyrach01/images/15190235/title/cool-dragon-wallpaper-wallpaper
http://www.google.com/imgres?q=sohma+shigure&um=1&hl=en&biw=1366&bih=643&tbm=isch&tbnid=Xj2rOMLUFEQilM:&imgrefurl=http://theotaku.com/cards/view/126364/appleadaykeepshatoriaway%25253F%25257