na-adjective
gentle; quiet; demure; mild-mannered
Describes a person's calm, reserved, and well-behaved nature. Often used for someone who is not loud or aggressive, with a nuance of modesty and propriety.
彼女は大人しやかで、いつもにこにこしている。
She is gentle and always smiling.
大人
He attended the meeting with a quiet, demure attitude.