Where is the source that says that Stiyl looking like an adult was due to art direction mistake?

Question

Where is the source that says that Stiyl looking like an adult was due to art direction mistake?

I remember something about "old" vs. "new", being interpreted wrong...

I think it was on the Toaru Majutsu no Index Wiki, but I'm not sure...

Answer 1

The Toaru Majutsu no Index Wiki does say it, on both Stiyl Magnus and Kanzaki Kaori's design evolution sections, but it doesn't actually give citations for its claims. The actual source is from Haimura Kiyotaka, the novels' illustrator, on his blog. A translation of Stiyl and Kanzaki's sections:

※ステイルは当初からイメージのズレが余り有りません。衣装は上からマント・ローブ・黒シャツ黒ズボンとなります。

　ちなみに、魔術側のキャラは１巻当時から、科学側のキャラに比べて年齢と外見の差異が著しいですが、 　コレには一応理由があったりします。詳しくは神裂のラフで後述。

There has not been much change in Stiyl's design from the very beginning. From top down, he wears a cape, a robe, a black shirt, and black pants. By the way, ever since their introduction in Volume 1, the gap between age and appearance in the magic side characters has been much greater than in the science side characters. There is a reason for this. See Kanzaki's rough for more.

※神裂はパーツが多かったので一番苦労しました。この段階ではジーンズのカットが随分と中途半端です。

　（ステイルの項から続き）１巻の本文初稿を読んだとき、はいむらが抱いた印象は、 　「…ああ、これは『オトナの理屈』に子供が反抗する話なんだな」なのでした。 　つまり、１巻時点の魔術側キャラであるステイルと神裂は、主人公である上条の目線からは、 　「子供にとって、嬉しくない建前や理屈を並べる大人」に見えたハズなのです。

　当時はさすがに、『禁書』がココまで長期に続くとは思ってもいなかったので、 　２名は上記の印象に従い、年齢不相応の造型にしました…そして、７巻辺りから徐々にそれを後悔する羽目に。

Kanzaki's design had a lot too it, so hers gave me the most trouble. At this stage, the cut of her jeans was only partway. (Continued from Stiyl's rough) When I read the first draft of Volume 1, I came away with the impression that it was the story of children rebelling against the reasoning of adults. That is why I thought Kamijou would have seen Stiyl and Kanzaki as adults that used reasonings and principles that a child would refuse to accept. At the time, I never thought Index would continue this long, so I went with my impression of the two and gave them designs that did not really match their ages...and by about Volume 7 I was starting to regret it.