さ is a 感動詞（かんどうし） (interjection) in Japanese that has three primary uses. These are as follows:
誘（さそ）い、促（うなが）し - To invite, incite, or draw attention to something.
驚（おどろ）き、当惑（とうわく）し - The express surprise, confusion, or bewilderment.
話（はなし）
の流（なが）れ
を抑（おさ）える - To control or keep in check the flow of a conversation.
In this lesson, we will be focusing on a specific feature of the first meaning (to draw attention). Unlike other types of drawing attention that
さ is able to be used for (see this grammar point), this
さ will only appear at the end of sentences. Here,
さ is almost identical in meaning to that of よ, with a slight added nuance of high confidence in what one is saying.
-
彼氏（かれし）がもう私（わたし）のことを信用（しんよう）できないってさ。
My boyfriend told me that he can't trust me anymore. (Added confidence gives the nuance of ‘can you believe it!’)
インスタで見（み）たんだけど、キヨミの赤（あか）ちゃんが明日（あした）生（う）まれるんだってさ！
I saw it on instagram, but I heard that Kiyomi is going to give birth tomorrow.
そんなこと心配（しんぱい）ないさ!俺（おれ）に任（まか）せとけ！
Such a thing is not necessary! Leave it to me! (Trust it to me in advance, so that it is not a problem later)
This
さ is primarily used by men, and can vary in meaning depending on the speaker’s tone of voice. However, in almost all situations
さ will mean ‘what I just said is correct’ (sometimes angrily, sometimes informatively, and even sometimes in a completely carefree way).
-
お前（まえ）さ...
You… (Are you freaking serious)
たかし君（くん）も行（い）きたいってさ。どうしよう？彼（かれ）も招待（しょうたい）する？
Takashi-kun said he wants to go too. What should we do? Should we invite him too?
そんなの俺（おれ）にだってできるさ。分（わ）からないけど。
Although I am not certain, even I would be able to do something like that.
Women may also use
さ as a sentence ender, but わよ tends to be more common.