On November 30, 1904, when the Imperial Army which faces an uphill battle attacked 203 high land under the strategy of the third commander Maresuke and the Army General Gentaro KODAMA, Yasusuke was hit by crump, fell down from a quay and crashed into rocks, and his head was pulverized and he died (immediate death).
明治37年11月30日、苦戦を強いられていた帝国陸軍は第3軍司令官・希典と児玉源太郎陸軍大将の戦略で203高地を進軍していたが、この時に保典が砲弾に打たれたショックで岸壁から滑落、岩場に激突し、頭が砕けて戦死した（即死）。