SuGoiSuす語彙すGrammar › N3 · 13 Particles and endings, more
さ: casual 'you know / of course'
N3 · 13 Particles and endings, more
Casual sentence-final or filler particle that states things as obvious.
Plain form + さ. Shows confidence or shrugs something off. Mid-sentence, it works as a filler: それでさ. Different from noun-making さ.
Examples
そんなの当たり前さ。
That's only natural.
どうなるかは分からないさ。
Who knows how it will turn out.