OP/ED Animation:
Tomoya Iwasawa (岩澤朋也)
Osamu Sasaki (佐々木理)
Hideki Kanou (加納秀紀)
Tomonori Okada (岡田智敬)
Maino Hikosaka (彦坂舞乃)
Junichi Yamamoto (山元隼一)
Oswaldo KATO (加藤オズワルド)

Yamamoto did direction, storyboard & unit direction: https://twitter.com/yamamotojunichi/status/1175004451385430017

本日発売のニンテンドースイッチ版「ゼルダの伝説　夢をみる島」のOP、EDムービー制作など参加しました。
ムービーのディレクションと絵コンテ、演出
などを担当しました！
子供の頃にクリアできなかったので、今度こそ
クリアしたいです！

KATO was in charge of the concept art, backgrounds and color design:
https://twitter.com/ozoztv/status/1174992615319564288

ゼルダの伝説夢をみる島発売おめでとうございます！
OP、EDムービーの制作に参加しました。コンセプトアート、色彩設計、BG、他いろいろ。大好きなタイトルなのでものすごく嬉しい！今度は本編にも参加したい！

Edit April 2021: It’s been a while and I did some more digging, was much easier to find info on the rest of the people now. The OP/ED is produced by Imagica Lab, and KATO and Yamamoto are pretty much the only people from the credits who’ve done 2D animation before (mostly just Yamamoto), so the animation here is likely by (one of) them. Both of them also stated doing some “other things” for the OP/ED as well, in addition to the roles they specifically mentioned.

For the time being, I’m presuming Yamamoto here since he’s a do-it-all man judging from his past works. While KATO has done some animation before, he’s more of an illustrator and a concept artist, and he has exactly one 原画 credit in anime, and even that was a super limited type of thing and not your “standard” anime. So I’m inclined to believe this is all Yamamoto.

Igettäjä said:
It’s been a while and I did some more digging, was much easier to find info on the rest of the people now. The OP/ED is produced by Imagica Lab, and KATO and Yamamoto are pretty much the only people from the credits who’ve done 2D animation before (mostly just Yamamoto), so the animation here is likely by (one of) them. Both of them also stated doing some “other things” for the OP/ED as well, in addition to the roles they specifically mentioned.

For the time being, I’m presuming Yamamoto here since he’s a do-it-all man judging from his past works. While KATO has done some animation before, he’s more of an illustrator and a concept artist, and he has exactly one 原画 credit in anime, and even that was a super limited type of thing and not your “standard” anime. So I’m inclined to believe this is all Yamamoto.

It's been a few years, and I want to do some research on who really animated this. While I am inclined to believe that the other people credited for OP/ED were not the key animators, considering that their only work before was CG, I am still puzzled why they are credited and what they are credited for, since there doesn't seem to be any CG in the opening. But to credit it all to Yamamoto also seems strange, since he has no previous work on the booru, and I don't have a source that he is a "do it all man" either. While he definitely did direct it and boarded it (and did unit direction? Not sure what this means in this context, since he did direction on the whole thing), it seems strange that he wouldn't take credit for KA, unless he didn't do KA. Because of that, I presume that this was either uncredited or NC. Also, after (very little) research on imagica lab, it doesn't seem to be an animation studio, but rather a post processing or 2ka kind of thing. But if they are a animation studio, I'd imagine that KA was done by one of their workers. And I would also like some sources on Kato doing KA, if it was Kato.