く Form as Adverb

    • Adjective
    • Adverb
    The く form can be used to turn い-adjectives into adverbs, in a similar way to "-ly" in English.

    Table of Contents

    The Basics

    One function of the く form is to turn い-adjectives into adverbs. In other words, the く form allows us to describe how an action is done. It’s quite similar to adding -ly to English adjectives (like happy) to form adverbs (like happily). Let’s see this in action:

    • 彼らは楽しく暮らしていました。
    • They lived happily.

    Adverbs in Japanese

    In Japanese, adverbs have a much wider range of use than their English counterparts. Take this sentence for example:

    • 私は京都に長く住んでいました。
    • I lived in Kyoto for a long time.
      ( Literally: I lived in Kyoto longly. )

    While it sounds weird to say "I lived in Kyoto longly" in English, this is a perfectly acceptable sentence in Japanese. The Japanese い-adjective 長い (long) can be easily transformed into the adverb 長く, but to express the same meaning in English we often have to use other structures (like the prepositional phrase "for a long time").

    This makes it much easier to describe how things are done in Japanese than in English:

    • そのラーメンを美味しく食べました。
    • I ate that ramen with gusto.
      ( Literally: I ate that ramen deliciously. )
    • ブロクを新しく作りました。
    • I made another blog.
      ( Literally: I newly made a blog. )
    • 難しく考えてしまった。
    • I thought about it in an over complicated way.
      ( Literally: I thought about it difficulty. )

    In general, all い-adjectives can function as adverbs when they are in the く form.

    Beyond the Basics

    Now that you know the basics, read on to learn about how く adverbs interact with the verbs する and なる.

    〜く with する to Indicate Willful Change

    When we pair a く form adverb with the verb する (to do), it indicates a change of state that is willfully caused by someone.

    • ペイントを使って、友子は部屋を明るくしました。
    • Using paint, Tomoko made her room bright.
      ( Literally: Using paint, Tomoko did her room brightly. )

    In this sentence, it's clear who caused the action, right? Tomoko is the one who "did her room brightly." So now, what if her room didn’t turn out as bright as she had hoped, and decides to make it even brighter? In English, we would use the comparative "-er” form of the adjective to describe the room changing from "bright" to "brighter." Japanese does not have such a comparative form for い-adjectives, so we’ll just add another word like もっと (more) if we’re being casual, or より (more) if we’re being formal, to accomplish the same thing:

    • ペイントを使って、友子は部屋をもっと明るくしました。
    • Using paint, Tomoko made her room brighter.
      ( Literally: Using paint, Tomoko did her room more brightly. )

    〜く with なる to Indicate Natural Change

    Pairing a く form adverb with the verb なる (to become) is used when the person who causes the change is not clear, or unimportant:

    • 子供達は大きくなっていた。
    • The kids have gotten big.
      ( Literally: The kids have become bigly. )

    As we know, kids grow up pretty quickly (too quickly, if you ask a sentimental parent). While most parents make sure their kids are well-fed, we can’t really say is the parents who cause them to grow up, right? In cases like this, we attach なる to the く form, for something like "become bigly."

    Again, because Japanese lacks a comparative "-er" structure, we can use a word like もっと here too to say that the kids have gotten bigger:

    • 子供達はもっと大きくなっていた。
    • The kids have gotten bigger.
      ( Literally: The kids have become more bigly. )