こそ

particle

it is ... that ...; precisely; definitely

Emphasizes the preceding word or phrase, often contrastively. Common in patterns like ～こそ～が, ～からこそ, and set phrases such as こちらこそ.

• 今年ことしこそ、日本にほん語ごをマスターしたい。

  This year, I definitely want to master Japanese.

• こちらこそ、よろしくお願ねがいします。

  It is I who should say that; pleased to meet you.

particle

although; while; it is the case that ... but

Used in the patterns こそあれ, こそすれ, こそするが, etc., to acknowledge a fact while contrasting it with another. Slightly formal or literary.

• 苦く労ろうこそあれ、得えるものも大おおきい。

  Although there are hardships, what you gain is also great.

particle

precisely because; only because

Follows the conditional -ba form of a verb, emphasizing that the reason given is the very cause. Often used in explanations or justifications.

• 努ど力りょくすればこそ、成せい功こうがある。

  It is precisely because you make an effort that success comes.

particle

not at all; absolutely not; never

Formal or literary. Follows the -nai stem of a verb + ば, creating a strong negative expression. Often used in emphatic denial.

• 彼かれの決けつ意いは揺ゆるがばこそ。

  His determination will not waver in the slightest.