で in 完全変態で、生まれ変わったように


I'm looking for some help in understanding the sentence below. To provide a
bit more context one of the characters シュン made a ”変態発言” and then the
following exchange occurred:

> Girl 1「”変態”って何ですか？」
>
> Girl 2「”さなぎから蝶になる”って意味よ」
>
> Girl 3「正確には完全変態」
>
> Girl 4「せんぱいって完全変態するんだぁ」
>
> Girl 1「シュン君は完全変態 **で** 、生まれ変わったように頑張るんですね」

I get the idea behind the exchange where 完全変態 is used to mean something like
Complete Pervert(referring to him being a pervert) / Complete Metamorphosis(as
in a type of metamorphosis in which the larva does not resemble the adult).
However what I've gotten myself confused on is how to properly parse the last
sentence.

I think I've just confused myself but anyway, is this で just simply であって and
not the で that is used with definitions like 動作・作用の原因・理由を表す,
動作・作用の手段・方法・材料などを表す。…を使って.




Girl 1: What does “hentai” mean?

Girl 2: It’s when a pupa turns into a butterfly.

Girl 3: Technically that’s “total hentai”.

Girl 4: Huh, so senpai goes through total hentai.

Girl 1: I see. Shun-kun is a total hentai, and that’s why he tries his best as
though he was reborn.

Girl 1 makes the connection that he tries as hard as he does because he’s a
total hentai. I think this is a であって usage of で and it somewhat expresses a
cause/reason. It’s a little different from 風で木が倒れた, where 風 is the 原因 for
木が倒れた, and で would _not_ mean であって because 風 is not being equated with
anything. In シュン君は完全変態で, there is an equation of two nouns, and hence this で
can be interpreted as the て form of だ. One of the usages of the て form is to
express a cause, e.g. 多すぎて in “人が多すぎて友達が見当たらない” (There’s too many people -> I
can’t find my friend.)




Girl 1: What does “hentai” mean?

Girl 2: It’s when a pupa turns into a butterfly.

Girl 3: Technically that’s “total hentai”.

Girl 4: Huh, so senpai goes through total hentai.

Girl 1: I see. Shun-kun is a total hentai, and that’s why he tries his best as
though he was reborn.

Girl 1 makes the connection that he tries as hard as he does because he’s a
total hentai. I think this is a であって usage of で and it somewhat expresses a
cause/reason. It’s a little different from 風で木が倒れた, where 風 is the 原因 for
木が倒れた, and で would _not_ mean であって because 風 is not being equated with
anything. In シュン君は完全変態で, there is an equation of two nouns, and hence this で
can be interpreted as the て form of だ. One of the usages of the て form is to
express a cause, e.g. 多すぎて in “人が多すぎて友達が見当たらない” (There’s too many people -> I
can’t find my friend.)

