Heard from someone that Samurai jeans fade unusually quickly. Never had a pair myself - been thinking over the past couple of days of getting the S710BK...
I know some SugarCanes fade quicker because of the sugar cane fibres woven in makes the mixed pure indigo come off easier (I remember my first pair of SCs, the Okinawas, the hem started fading after a week =D). Don't know about Samurai's. Maybe because of the high denim weight?
Well, other than SugarCane, my favourite Japanese jeans maker has to been Studio D'Artisan

They make them so well - the attention to detail appealed to me. And the pigs, got to love the pigs =P