こそ (romaji koso)
- (Emphatic particle, is used for emphasis. There is no direct translation, but it is roughly analogous to "precisely".)
- kyō koso, yaru zo!
- Today is when I'm going to do it!
- Kimi ga suki dakara koso kore hodo ganbatte irunda yo.
- It's precisely because I like you [because of my fondness for you] that I'm working this hard.