It's not an easy task to speak up/voice concerns to higher-ups in Japan.
Speak up to /voice concerns to ; 意見する。
Higher-ups;お偉いさん
Higher management; 上役
Japanese honorifics defines the hierarchical relationship relatively more than other languages, which developped the particular environment where the employee find it difficult to speak up to his boss.
日本の敬語は他の言語よりヒエラルキーをはっきりさせてしまい、それが上司に意見を言うのが難しい環境を作ってしまった。