The word for “good” is yoi 良い. However, it is not as easy as simply using it as the opposite of warui 悪い. The first problem we encounter is that it’s usually replaced with its contracted form: ii いい. However, it is yoi 良い that is used for conjugation. There is also the problem of nuance, which is the hardest problem for learners.
When you conjugate yoi/ii よい・いい, you must use yoi よい for everything aside from the non-past tense.
|Form||Plain Speech||Polite Speech|
|Non-past||Yoi/ii よい・いい||Yoi desu/ii desu よいです・いいです|
|Past||Yokatta よかった||Yokatta desu よかったです|
|Negative||Yokunai よくない||Yokunai desu よくないです|
|Negative Past||Yokunakatta よくなかった||Yokunakatta desu よくなかったです|
|Te て Form||Yokute よくて||Yokute よくて|
|Adverbial Form||Yoku よく||Yoku よく|
In the example sentences below, yoi/ii よい・いい are used in the various forms above with nuances that all revolve around “good (for)/fine/excellent/pleasant/agreeable/ready/sufficient/beneficial/okay.”
Seiseki ga yoku natta.
My grades become good/got better.
Konshū wa (o)tenki ga yokunai desu ne.
The weather this week isn’t good, huh.
Un ga yokatta desu ne.
My/our/your/his/her luck was good, huh.
Kare wa kakko yokute yasashii desu ne.
He is cool and nice, isn’t he?
Phrase Note: Kakkō yoi 格好良い means “attractive/good-looking/stylish,” and in the spoken language, it is typically contracted to kakko ii かっこいい. It is frequently alternatively spelled as カッコいい.
Inshō ga yokunakatta desu.
Its impression wasn’t good.
Jūgyōin no taiō ga yokunakatta.
The employees’ handling wasn’t good.
Yoi o-toshi wo!
Have a good New Year!
Phrase Note: This phrase is more or less the same as saying “Happy New Year” in the West, and as such, it is not used once the New Year has begun. Even in the spoken language, /yoi/ is still the predominant pronunciation in this set phrase. However, /ii/ would not be wrong.
Sore wa yokatta desu ne.
I’m glad to hear that.
Sentence Note: One could more literally be expressed as sore wo kiite yokatta desu neそれを聞いてよかったですね. However, this would emphasize being glad that you heard whatever “that” is.
Tabako wa karada ni yokunai desu.
Tobacco is not good for the body.
Spelling Note: Tabako may be alternatively spelled as たばこ or 煙草.
Ii keshiki desu ne.
What nice scenery, no?
Sentence Note: This may be more literally expressed by adding the adverb nanto なんと at the beginning of the sentence, but because this is very emphatic, the adjective subarashii 素晴らしい (wonderful) would be more appropriate.
Kare mo ude ga ii desu yo.
He too has good skill.
Phrase Note: Ude ga yoi/ii 腕が良い is a set phrase meaning “able/skilled,” and both /yoi/ and /ii/ are correct pronunciations; however, the latter is most common in the spoken language.
Tōnōbyō ni yoi shokuhin wo oshiete kudasai.
Could you please tell me foods that are good for diabetes?
Spelling Note: As you may have noticed, writing yoi/ii よい・いいin Kanji usually indicates that the pronunciation is /yoi/. Although this not a guarantee, it shows that the sentence is stilted to the written language.
Kakugo wa ii ka?
Tone Note: This sentence is both casual and indicative of a superior-inferior relationship. Meaning, the speaker is in no way below the listener in status.
Aishō ga yoi/ii kappuru no tokuchō wa nan desu ka?
What are the characteristics of a couple that suits each other.
Phrase Note: Aishō 相性 means affinity, and so aishō ga yoi/ii 相性が良い literally means “affinity is good.” The opposite of this is aishō ga warui 相性が悪い.
Eiga wo mite yokatta desu.
I’m glad I watched a/the movie.
Grammar Note: Te yokatta てよかった is used to mean “I’m glad that (I)…” It may be used in reference to being glad that an action was done or that a particular situation came to be.
Spelling Note: Spelling miru as 観る indicates that you watched the movie somewhere, most likely a theatre.
Rejecting an Offer
Just as in English with the word “fine,” ii may be used in rejecting offers.
Ē, ii desu yo.
Sure, that’s fine.
(Iya,) ii desu.
(No,) I’m fine.
However, just as in English, many people just don’t get it and do whatever you intended to say “no” to anyway.
1. When 良い’s nuance focuses on the nature/behavior/actions/status of someone/something is satisfactory, it may be alternatively spelled as 善い. However, this is rather rare in today’s writing.
2. When 良い's nuance focuses on the auspicious nature of something, then it may be alternatively yet rarely spelled as 好い, 佳い, or 吉い. Unless you read works of the famous Natsume Sōseki 夏目漱石, you’ll likely never see them.
As an extension of rejecting with ii, it may also be used in an insulting/ironic manner in several set phrases.
Mō ii desu.
Sentence Note: Even in English, this phrase may be quite offensive depending on the situation.
Ii kagen ni shite kudasai!
Please cut it out!
Ii toshi (wo) shite jikkagurashi wa hazukashii.
Living at one's parents’ house despite being old enough to know better is embarrassing.
Phrase Note: Ii toshi (wo) shite いい歳（を）して is a set phrase used to insult someone for something that is unbecoming of his age. Jikkagurashi 実家暮らし is a set phrase meaning living with one’s parents, particularly at their home.
Anta, ii meiwaku da yo.
You’re a real nuisance.
Phrase Note: Anta あんた is a coarse contraction of anata あなた (you). Only in non-Standard Japanese dialects is it used in a less casual and coarse manner. Male speakers of Arabic should especially take caution in not overusing it as it may be tempting to use it due to it coincidentally sounding like the word for “you.”
Ii zama da.
It serves you/him/her right!
Ii kimi da.
It serves you/him/her right!
Phrase Note: This is synonymous to Ex. 23. Kimi literally means “feeling/sensation” and zama ざま literally means “sorry state.” It may also be seen as a suffix attached to verb stems to mean “manner of.” For example, ikizama 生き様 means “way of life.”
Ii go-mibun da ne.
How can you afford it?
Phrase Note: Go-mibun ご身分 is literally a respectful phrase referring to someone’s status. Here, it is being used sarcastically to lead to a question about how the other person could possible afford the item of discussion.
Spelling Note: Although not really common at all, these negative nuances of ii いい may be spelled in Kanji alternatively as 好い.
There are plenty of set phrases in which yoi/ii よい・いい are attached to nouns to create a compound expression. In this case, the main difference is typically whether the sentence is made for the written or spoken language. For the written language, yoi よい will be your choice, and for the spoken language, ii いい will be your choice.
Asaburo mo kimochi-yoi/ii.
The morning bath also feels good.
Toritachi no kokochi-yoi/ii saezuri ni mimi wo katamukeru.
To listen carefully to the pleasant songs of the birds.
Phrase Note: Mimi wo katamukeru 耳を傾ける literally means “to tilt one’s ears.” Kokochi 心地 means “sensation,” and it is seen following the stem of verbs as gokochi to show the “sensation of doing.” In which case, these phrases are very frequently followed by yoi/ii よい・いい.
Grammar Note: -tachi たち is a suffix that indicates a group of something.
Spelling Note: Although rare and difficult, saezuri may be alternatively written in Kanji as 囀り.
Igokochi-yoi/ii basho de tokubetsu na jikan wo sugosu.
To spend special time at a cozy place.
Kōsō manshon no saijōkai wa sumigokochi-yoi no desu ka?
Is it comfortable living on the top floor of a high-rise apartment complex?
Reading Note: Due to the presence of no desu ka のですか, it becomes more unlikely that 良い is read as /ii/.
The adverbial form yoku よく may be used to mean “nicely/well” or “frequently/often,” but differentiating between these usages will require contextual clues.
Ha wo yoku migaite kudasai.
Brush your teeth well.
Kare wa hontō ni yoku ha wo migaite iru ka dō ka wakarimasen.
I don’t really know whether or not he brushes his teeth often.
Yoku yarimashita ne.
Wow, you did well.
Ano ko wa okā-san to yoku nite imasu ne.
That child closely resembles his/her mother.
Sore, saikin yoku kikimasu ne.
You here that a lot recently, don’t you.
Yoku denwa suru aite wo tōroku suru.
To register those one often calls.
Watashi wa yoku piza wo chūmon shimasu.
I often order pizza.
Ichigo wo yoku tabemasu ka.
Do you often eat strawberries?
Spelling Note: Ichigo may alternatively be spelled in Kanji as 苺.
Yoku kiite kudasai.
Please listen closely.
Kare wa, tegiwa yoku shokki wo kasanete imashita.
He was skillfully stacking tableware.
Sono kame wa un yoku nagaiki shimashita.
The turtle luckily lived a long life.