乙川と矢作川の合流点に隆起する龍頭山は天然の要害です。三河国一の勢力となった家康の祖父松平清康は、そこに統治の拠点となる大城郭岡崎城を築きました<br />たおやかインターネット放送ＨＰ：http://taoyaka.at-ninja.jp/ <br />The ryuutou mountain that rises at the confluence of the Otogawa and Yahagi Rivers is a natural hazard. Ieyasu's grandfather Kiyoyasu Matsudaira, who became the most powerful force in the Mikawa country, built the Oshiro Guo Okazaki Castle as the base of governance there<br />Taoyaka Internet broadcasting website: http://taoyaka.at-ninja.jp/
