Using the Particle こそ to Add Emphasis
The particle こそ is used to add emphasis to the word, clause, or even phrase, immediately preceding it. As the usage of こそ is highly contextual and there is no English equivalent, it can be difficult to translate. Common translations include: “for sure,” “very,” “precisely,” “in particular,” “exactly,” “only,” “definitely,” etc.
The particles は, が and を are dropped when こそ appears in their place. Other particles such as で and に however do not drop when こそ is employed and they instead appear preceding it (e.g. それでこそ)
こそ perhaps most commonly follows after NOUN words, in which common types of such NOUN words are time-related words (今こそ, 今日こそ, 明日こそ, 今年こそ, 今度こそ, etc.) and demonstrative pronouns (これこそ, それこそ, こちらこそ, etc.).
Kondo wa untenmenkyo o shutoku suru!
“I will obtain my driver’s license next time!”
Kondo koso untenmenkyo o shutoku suru!
“I will obtain my driver’s license next time for sure!”
Ima koso koudou no toki da.
“Now is the time for action.”
Ai koso ga subete da.
Love especially is everything.
Hajimemashite. George Washington desu. Yoroshiku onegaishimasu.
”How do you do? George Washington. Pleasure to make your acquaintance.“
Kochira koso yoroshiku onegaishimasu.
“The pleasure is all mine.”
Kono aida wa arigatou gozaimashita.
“Thank you very much for what you’ve done.”
Kochira koso, arigatou gozaimashita.
“I’m the one who should be thanking you. Thank you very much.”
Another very common way in which こそ is used is in which it appears after the conjunction から (“because”) to emphasize the reason behind something, translating to something along the lines of “precisely because,” “exactly why,” etc.
Mainichi renshuu shita kara koso, tsuyoku natta.
“It’s precisely because you practiced every day that you’ve become strong.”
Bouken dakara koso omoshiroi!
“It’s an adventure, that’s exactly why it’s so fun!”
Shinpai suru kara koso, shikaru yo.
“The only reason why I scold you is because I care about you.”
こそ can also appear after VERB words without the addition of the conjunction から. When doing so, the VERB words are usually conjugated into their て-Form to emphasize a certain condition and this translates to something along the lines of “only by doing VERB, X.” However, a less common usage of VERB words in their Conditional ば with こそ also exists, in which the meaning is the same as からこそ.
Mainichi doryoku shite koso, me ni mieru kekka ga arawareru.
“Only when you put in effort every single day will you be able to see the results appear before you.”
Jibun be yatte mite koso, kachi ga wakaru.
“Only when you try it for yourself will you be able to realize the value in it.”
Shouko ga areba koso hannin o mitsuketa.
“We were able to determine the culprit only because we had the evidence.”