In the present study, undertaken in Tsuyama City, Okayama Prefecture, we have investigated the change of the housing plan from samurai houses to urban independent residences, from the Meiji to Showa eras (before world war II). We aimed to clarify the succession and the modification of the "front facing principle", the primary factor underlying the modification, and the time of the modification. Conclusions; (1) The "zashiki" rooms of samurai houses in the Tsuyama feudal clan faced the front entrance of the land following the so called "front facing principle". In addition, there was a ground plan unique to the Tsuyama feudal Clan. (2) This "front facing principle" and Tsuyama's unique ground plan have been succeeded by matcing plan of urban independent residences build after the Meiji Era, that is, south facing "zashiki" on south facing land and north facing "zashiki" on north facing land. (3) South facing "zashiki" rooms on the north facing lands, however, emerged in the Taisho and early Showa eras. (4) The lateral arrangement of "zashiki" rooms in samurai houses shifted to the tandem arrangement after the Meiji Era.