Describes doing something without restriction, as one wishes, or with effortless control. Often used with verbs of movement, manipulation, or operation.
See also: 自在
He operates the computer with ease.
With this tool, you can freely change the shape.
Adverbial form of 自在 (じざい), which is a Sino-Japanese word from 自 (self) and 在 (exist, be at). The combination conveys the idea of being in one's own control, hence 'freely, at will'.