The project is a passionate one that comes from Saku Sakamoto as they did original concept, script, music, and the animation for it.
The Japanese cast includes Kana Hanazawa as Rin, Ayana Shiramoto as Nasuha, Fukujurō Katayama as Saion, Shōgo Batori as Mikaya, and Yōsuke Itō as Tokiyo.
The distributor has set up a virtual festival for it that you can find here through eventive or through their own offering here (which uses eventive but more detailed).