usually a clan crest or something like that
the tattoos can range from full body to *most of the time* full back and sleeves down to the wrists.
there is a distinctive style to them
many times a koi/dragon/kabuki figure/etc.
the tattoos are done has one solid piece, so the back will link to the sleeves and legs and such.
other words
you see some one with a dragon on his arm or tribal, or kanji
it doesnt mean hes yakuza.
You see some one with tattoos from his neck to his wrists.. then you have your self a yakuza style tattoo.
just do a google search you'll see the style im talking about.
and yes you will not be able to get into many onsens with tattoos.
i've tried, and was denied horribly =P
there are gaijin onsens.... if you wana take baths with fatty foreigners.. but that wasnt for me sooo ill just have to pass on that experience.
Plus i can go in the bathhouses in vietnam w/o a problem and get the same experience.
i have heard of some places letting you slide with a few small pieces done... but i have my entire back tattooed. so that was a no go.
