I know that 別に means "not particularly" sometimes, but what is its role in
this sentence?

別に山田の私服を見るのは、はじめてってわけじゃないんだけどな。

I assume it means something like "it's not exactly the first time I've seen
Yamada in plain clothes", but I don't know what exactly 別に is doing or what
verb it's modifying.
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2015-01-18T19:02:20.647
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2020-02-29T12:01:32.120
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question
grammar
How does 別に function as an adverb?
Certainly. [The definition given in
大辞林](http://www.excite.co.jp/dictionary/japanese/?search=%E5%88%A5%E3%81%AB&match=beginswith&itemid=DJR_betuni_-010)
is below.

> > （ 副 ） （下に打ち消しの語を伴って）取り立てて言うこともないという気持ちを表す。とりたてて。特別に。 「 －用はありません」 「
> －変わった様子もない」 〔その話題を軽く拒否する気持ちを表す。応答の言葉として，感動詞的にも用いられる。「『寒くないか』 『－』」〕

So as you said, "not necessarily need to mention 〜", "It goes so particularly
without saying..." etc?

And what it modifies is the postpositional particle ぬ or ない, which denotes the
denial of the noun, noun phrase, adjective, etc, which comes "before" ぬ or ない。

Ex : 今日は別に寒くない。--> Today, it is not cold especially.
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2015-01-18T21:12:12.297
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2015-01-18T22:18:59.340
2015-01-18T22:18:59.340
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answer