We met the adverbial noun よう previously when we looked at ways to express similarity in Japanese. Its other grammatical usage is to express a change of state from A to B.
【Verb: Dictionary】ようになる
テニスに興味を持つようになりました。
I have come to take an interest in tennis.
Essentially all we are doing is modifying the adverbial noun よう to describe the new “state” or “condition” and then appending the verb “to become” (なる) to express the change.
Habit vs. Ability
よう is very often used with the potential form of the verb. It is important to distinguish between using a standard verb and a potential verb here.
Standard Dictionary Verb: Expresses a change in habit (I started doing X).
Potential Verb: Expresses a change in ability (I became able to do X).
できるようになる。
To become able to do (To reach the point where one can do something).
日本に来てから、お箸をうまく使えるようになりました。
After I came to Japan, I became able to use chopsticks well.
スマホが普及してきたらアプリだけでお金を振り込めるようになった。
As smartphones have become prevalent, we are now able to transfer money through just an app.
政治史を学ぶと時事問題の背景を理解できるようになる。
If you study political history, you will become able to understand the background to current issues.
Negative Change of State (なくなる)
While not grammatically incorrect, ～ないようになる is rarely used to describe a loss of ability. Instead, the final い of the negative verb is treated as an i-adjective, turned into an adverb, and appended directly with the verb “to become”.
～ないようになる ⇒ ～なくなる
ほら、おもちゃをあげると泣かなくなるよね。
You see, he stops crying if you give him a toy.
できなくなる。
To become unable to do.
年を取ると、長い距離を走れなくなる。
You won’t be able to run long distances once you get older, you know.
大雪のため、家を出られなくなった。
I am no longer able to leave my house due to heavy snow.
最近は少し太ってきて、大好きなドレスを着られなくなったのよ。
Recently I’ve put on a little weight and I can no longer wear one of my favourite dresses.
Modifying Nouns
Remember that よう is an adverbial noun, so we can modify other nouns with the な particle just as we would with a na-adjective.
もうお酒を飲んだので、運転できるような状況じゃないね。
I’ve already had a drink, so I’m not in a condition where I can drive.
彼は信頼できるような男じゃないよね。
He’s not the kind of guy you can trust, right?
Expressing Purpose: ように (So that…)
よう can also be used with verbs other than なる. This allows us to show that an action was taken for a specific purpose or that a change was deliberately instigated (as opposed to being a natural consequence).
翌日の午前８時に出勤するように指示する。
Instruct someone to arrive at work for 8am the following day.
When expressing a negative purpose (“so that X doesn’t happen”), we must use the structure with ないように. (We cannot use なくなる here, because なくなる expresses a result, whereas ないように expresses intent).
人が入らなく鍵を閉めておいてください。(✘)
人が入らないように鍵を閉めておいてください。
Please lock the door so that people will not enter.
貴重品を持って帰るのを忘れないようにしてください。
Please take care so that you do not forget to take home any valuables.
インフルエンザにかからないように、予防注射を受けます。
Get a flu shot so that you don’t catch influenza.
Note how we can change the ending verb to make more complex sentences about effort and purpose.
今日は早く帰れるようにする。
Today I’ll make an effort so that I can go home early.
今日は早く帰れるように頑張る。
Today I’ll try hard so that I can go home early.
今日は早く帰れるように仕事しながらランチを食べる。
Today I’ll work while eating lunch so I can go home early.