The manga began in 2016 in the magazine and there are twelve volumes out as of this week.
We learned back in September 2019 from the Weekly Shounen Sunday magazine that an anime adaptation of the Sleepy Princess in the Demon Castle manga from Kagiji Kumanomata is in the works.
We’re still figuring on it being a fall 2020 show but anything goes at this point until the official site reveals things.