平山城 ひらやまじろ Also written ひらさんじょう Meanings Noun castle on a hill in the plains; flatland-mountain castle See also: 平城 (ひらじろ). See also: 山城 (やまじろ). Kanji 平 flat. Read as ひら. 山 mountain. Read as やま. 城 castle. Read as しろ. Jinuma: Japanese Dictionary · Word lists