Those 3 are biggest Japanese online stores that ship overseas. Spinfactory.de offers a few Darker blades, too: https://www.spinfactory.de/tischtennis-hoelzer/tischtennis/darker.html
Fourteen VICTAS 90th Anniversary limited edition blades will be released in December 2021:
https://www.victas.com/ja_jp/info/related_news/victas/important_news/90th_anniversary_limited_edition