mild-mannered

calm, gentle, moderate and unexcitable in attitude

Japanese Meaning

落ち着いた / 温和な / 穏やかな / おとなしい

The mild-mannered librarian surprised everyone by leading the protest with quiet conviction.

温和で穏やかな司書は、静かな確信を持って抗議を率い、皆を驚かせた。

Sense（1）

calm, gentle, moderate and unexcitable in attitude

more mild-mannered

（ comparative ）

most mild-mannered

（ superlative ）