Sangaku Engi Settei (Patreon)

Today I've added settei for Sangaku Engi, but this one is a bit different, since it hasn't actually aired yet. 

I couldn't find much information about this, except that it was announced by Haoliners Studio in 2016 and it made a brief appearance in a short trailer announcing it. It appears to be an adaption for this light novel. Since it's been eight years since the announcement, I kind of assume it's been cancelled.