助詞N3
〜こそ
exactly... / precisely... (emphasis)
Structure
N + こそ；V-て形 + こそ
Explanation
Emphasizes a specific item, "exactly... / precisely...". Attaches to nouns or the te-form + こそ (これこそ本当の日本料理だ).
Examples
これこそ、私たちの求めていた製品です。
This is exactly the product we were looking for.
今度こそ、試験に合格したいです。
This time for sure, I want to pass the exam.
Note
koso emphasizes a particular item. In speech, こそ...よ is used to echo the other person's words.