Koinoriko will be changed.

GM has announced that Koinoriko (fish) will be changed not to drop rare materials after the patch on 18th Nov. in JP server.
After the patch, Koinoriko drops chocolate pie instead of rare materials.

And there will be another way to get rare materials in the near future.

http://kunshu.ndoors.jp/center/news/news_view.asp?board_idty=100&list_seq=3044&page=1