に Adverbial Copula

In Japanese, the ni に particle is sometimes an adverbial copula.

Grammar

Grammar

The ni に copula is sometimes called an "adverbializer" because it turns words into adverbs. However, it isn't actually a generic adverbializer. It's simply the adverbial form of the da だ copula.

hontou da
本当だ
[It] is true.
hontou ni sou da
本当にそうだ
[It] truly is that way.

To elaborate: when nouns and na-adjectives are used as the predicate of a subject, the predicative da だ copula comes after them. (except it's omitted in most simple sentences.)

neko wa doubutsu da
猫は動物だ
Cats are animals.
- neko wa - topic, subject.
- doubutsu - noun, no-adjective.
- doubutsu da - predicate.
neko ga suki da
猫が好きだ
Cats are liked.
[I] like cats.
- neko ga - small subject.
- suki - na-adjective.
- suki da - predicate.

With i-adjectives, however, the ~i ～い suffix itself is said to be a copula, and da だ isn't used.

neko wa kawaii
猫は可愛い
Cats are cute.

Consequently, the ni に adverbial copula can adverbialize nouns, or no-adjectives, and na-adjectives, which take the da だ copula, but it can't adverbialize i-adjectives, which don't take the da だ copula.

For i-adjectives, the adverbial form would be the ~ku ～く suffix instead.

{futsuu no} hito
普通の人
A person [that] {is normal}.
A {normal} person.
{futsuu ni} aruku
普通に歩く
To walk {in a way [that] is normal}.
To walk {normally}.
- futsuu ni 普通に
  Normally. (without alteration.)
- fudan ni 普段に
  Normally. (often.)
{jiyuu na} hito
自由な人
A person [that] {is free}.
A {free} person.
- jiyuu 自由
  Free. (of freedom.)
- muryou 無料
  Free. (of charge.)
{jiyuu ni} aruku
自由に歩く
To walk {in a way [that] is free}.
To walk {freely}.
{hayai} hito
速い人
A person [that] {is fast}.
A {fast} person.
- hayai 速い
  Fast. (speed.)
- hayai 早い
  Fast. (early.)
{hayaku} aruku
速く走る
To walk {in a way [that] is fast}.
To walk {quickly}.

As with everything related to copulas, ni に copula doesn't necessarily come after a single word. It can come after an entire clause, provided that such clause would've ended in the da だ copula predicatively.

{{{hontou ni} sugoku} kawaikute kirei na} neko da
本当に凄く可愛くて綺麗な猫だ
[It] is a cat [that] {is {{really} incredibly} cute and pretty}.
{{{{hontou ni} sugoku} kawaikute kirei na} neko ni} naru
本当に凄く可愛くて綺麗な猫になる
To become {a cat [that] {is {{really} incredibly} cute and pretty}}.

Although the ni に copula can adverbialize most words that take the da だ copula predicatively, there are some exceptions. Mimetic words and taru-adjectives sometimes take the to と particle instead in adverbial form.

urouro to aruku
うろうろと歩く
To walk aimlessly.
doudou to aruku
堂々と歩く
To walk magnificently.

になる, にする

The greatest hurdle related to the ni に copula is the ergative verb pair naru なる and suru する.

The verb naru なる means "to become," while suru する is, sometimes, the lexical causative of naru なる, meaning "to cause [something] to become."

In English, when you say "I'll become a cat," for example, the noun phrase "a cat" looks like it's the direct object for the verb become. However, "to become" is actually intransitive.

If it was a transitive verb, you'd be able to say the passivization "a cat will be become by me," the same way you can say "I'll drive a car," and "a car will be driven by me." Since you can't do that, the verb isn't transitive, it's intransitive.

It isn't "you become something," with a noun, it's "you become somehow," with an adverb.

Similarly, naru なる isn't a transitive verb in Japanese. So it doesn't take the wo を particle, which marks the direct object. It only, in some cases, takes the ni に particle. Not because it marks the indirect object, but because it makes word into an adverb.

*neko wo naru
猫をなる
(wrong, naru doesn't take a direct object.)
neko ni naru
猫になる
To become in such way {[you] are a cat}. (literally.)
To become a cat.

This is evidenced by the fact the same thing happens with i-adjectives: you don't mark them with ni に, you use their adverbial forms:

*kawaii ni naru
可愛いになる
(wrong.)
kawaiku naru
可愛くなる
To become in such way {[you] are cute}.
To become cute.

Some other examples:

konagona da
粉々だ
[It] is in-pieces.
{konagona ni} naru
粉々になる
To become in-pieces.
To turn into pieces.
{konagona ni} shite-yaru!
粉々にしてやる！
[I] will make [you] into pieces!
- Generally used by evil guys to say they'll murderize someone.

shizuka da
静かだ
[It] is quiet.
{shizuka na} machi
静かな街
A {quiet} town.
{shizuka ni} naru
静かになる
To become {quiet}.
{shizuka ni} shi-nasai!!
静かにしなさい！！
Make [it] {quiet}!!
SILENCE!!

Other Intransitives

The verbs naru なる and suru する aren't the only intransitive verbs to watch out for. Another pair of verbs are mieru 見える and kikoeru 聞こえる, which mean something can be "seen" and "heard" somehow, respectively.

{kawaiku} mieru
可愛く見える
[It] seems cute.
{kirei ni} mieru
綺麗に見える
[It] looks pretty.
{uso ni} kikoeru
嘘に聞こえる
[It] sounds {a lie}.

Auxiliaries

There are a number of suffixes and auxiliaries that make use of the ni に copula in the adverbial form. Some examples include:

{{neko no} you ni} mieru
猫のように見える
[It] looks {in a way that is the appearance {of a cat}}.
[It] looks {like {a cat}}.
- you 様 - a formal noun.
{seiri-teki ni} muri
生理的に無理
{Physiologically} impossible.
- In anime, generally used when a girl says she will never date a guy because she's disgusted by him at a physiological level.
- teki 的 - a suffix conjugated like a na-adjective.
{oishi-sou ni} taberu
美味しそうに食べる
To eat [it] {like [it] is tasty}.
- sou そう - a jodoushi 助動詞, "helper verb," conjugated like a na-adjective.