What does い adjective くform + noun signify?


The title of
[this](https://www3.nhk.or.jp/news/easy/k10011444081000/k10011444081000.html)
news article is

> 将棋の[藤井]{ふじい}[聡太]{そうた}さん 今まででいちばん若く「[七段]{しちだん}」になる

Why is 若く used here instead of 若い? As far as I know, い adjectives change into
く form when they come before verbs but 「七段」に なる doesn't seem like a verb here.
What does this kind of grammatical usage of い adjective signify ? Examples
would be nice.

Thank you :)




As Sjiveru says, it's an adverb modifying a verb phrase. Saying that
い-adjectives change to く form before a verb is an oversimplification; く form
is the adverbial form.

This a tricky sentence because we would use an adjective in English, so let's
look at another example.

> I ran quickly to the store.

As you can see, "quickly" is an adverb modifying "ran." Now, in Japanese:

> 速く店まで走った。

The word order here is perhaps a bit awkward, but you can see that 速く isn't
modifying 店, it's modifying 走った. If you changed it to:

> 速い店まで走った。

It wouldn't make any sense. What's a fast store?

Now, to the original headline:

> 将棋の藤井聡太さん 今まででいちばん若く「七段」になる

Fujii-san is the youngest Shōgi player to attain 7th level. Or in headline-
speak "Shōgi's Fujii Souta-san youngest to attain 7th level"

If you changed 若く to an adjective, it would mean that Fujii-san is "becoming
the youngest 7th-level." This is awkward if not ungrammatical, because unlike,
say, "black-belt," "7th-level" is somewhat unnatural as a metonymy for "7th-
level player".

Note: I know nothing about Shōgi, so I'm not sure if "7th-level" is a natural
translation or if we'd say "7-dan" or something else in English!

