Today, from his official X account it was announced that Amisu (haitokukan) passed away on February 28, due to acute circulatory failure.
This was his last illustration he made.
RIP

You are the best, thank you for all your work
and especially your last gift to us

He has some of the best Touhou Doujins I ever seen, thanks for everything.

Thank you for everything, Amisu. I hope you're in a better place now.