* これは良くない (Kore wa yoku nai): This is a general and safe option. It means "This is not good" and works for many situations where something is unpleasant or undesirable. It's neutral and doesn't carry strong emotion.
* これは嫌だ (Kore wa iya da): This means "This is unpleasant" or "I dislike this." It's more subjective and expresses personal feeling.
* これは親切じゃない (Kore wa shinsetsu ja nai): This translates to "This isn't kind" or "This isn't nice" specifically in the sense of being unkind or inconsiderate.
* これは不愉快だ (Kore wa fuyukai da): This means "This is unpleasant" or "This is disagreeable," suitable when something is offensive or makes you feel bad.
* これは気に入らない (Kore wa ki ni iranai): This translates to "I don't like this" or "This isn't to my liking." It focuses on personal preference.
To choose the best translation, consider:
* What is "this"? Is it an object, an action, a situation?
* Why is it not nice? Is it unkind, unpleasant, of poor quality, etc.?
* What is your level of formality? These phrases can be adjusted for politeness level.
For example:
* If someone did something mean: これは親切じゃない (Kore wa shinsetsu ja nai) or それは良くない (Sore wa yoku nai) would be appropriate.
* If you dislike the taste of food: これは気に入らない (Kore wa ki ni iranai) or これは美味しくない (Kore wa oishiku nai - This is not delicious) would be better.
* If something is simply unpleasant: これは不愉快だ (Kore wa fuyukai da) or これは嫌だ (Kore wa iya da) would work.
Therefore, there's no single perfect translation. Providing more context will help determine the most accurate and natural-sounding Japanese phrase.