Change & Becoming: 〜になる, 〜くなる, 〜てくる
Japanese has precise grammatical structures for describing change. になる (become a noun/state) and くなる (become more adjective) are N5 essentials. Adding てくる and ていく lets you describe change toward the present or continuing into the future.
〜になる: becoming a noun or な-adjective state
Attach になる to nouns or な-adjective stems to say "become X". This is one of the most common structures in everyday Japanese.
〜くなる: becoming more of an い-adjective
For い-adjectives, drop the final い and add くなる to express that something is becoming more that way.
〜てくる: gradual change toward now
Combining a change verb with てくる marks gradual change that started in the past and has arrived at the present moment. It emphasises the process of becoming.
〜ていく: change continuing into the future
ていく after a change expression marks a change that is happening now and will continue forward in time — the opposite direction from てくる.
Common mistakes
元気なくなった (い-adj rule applied to な-adj)
Right元気がなくなった or 元気じゃなくなった
元気 is a な-adjective, so it does not take 〜くなる directly. Use になる/じゃなくなる for な-adjectives and nouns: 元気じゃなくなった (became not energetic) or 元気になった (became energetic).
ようになった for sudden ability gain
Rightようになった marks gradual ability — not a sudden switch
〜ようになった (came to be able to) implies gradual acquisition over time. For something enabled by a single event, use simply できるようになった with appropriate context showing process, not a single instant.
てくる and ていく are interchangeable
Rightてくる = change arriving at now; ていく = change going forward from now
「寒くなってきた」= It has been getting cold (and is cold now, change arrived). 「寒くなっていく」= It will keep getting cold (change going forward). The temporal direction is the key distinction.
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How do you say "become" in Japanese?
Use になる for nouns and な-adjectives: 医者になる (become a doctor), 静かになる (become quiet). Use 〜くなる for い-adjectives: 寒くなる (become cold), 大きくなる (grow bigger). For ongoing gradual change reaching the present: 〜てくる. For change continuing into the future: 〜ていく.
What is the difference between になる and くなる?
The choice depends on the adjective type. い-adjectives: drop い, add くなる → 高い→高くなる (become expensive). な-adjectives and nouns: add になる → 静か→静かになる (become quiet), 先生→先生になる (become a teacher). Applying くなる to a な-adjective is a common learner error.
How do I express gradual change in Japanese?
Combine a change expression with てくる (toward now) or ていく (into the future). 「だんだん上手くなってきた」= I have been gradually getting better (at this point). 「これからも上手くなっていく」= I will keep getting better from now on. Adding だんだん (gradually) or 少しずつ (little by little) reinforces the gradual nuance.