noun
nice guy; pleasant fellow; good-natured man
Describes a man with a cheerful, open, and agreeable personality. Often used in a somewhat literary or dramatic tone, but not archaic.
彼は誰からも好かれる快男児だ。
He is a nice guy liked by everyone.
あの快男児ぶりには感心するよ。
I admire his pleasant, good-natured manner.