Less Kagerou x Wakasagihime than I was expecting, but still very cute and wholesome nonetheless. I'm guessing this takes place in the same universe as The Grilled Fish's Ballad, given how Kaguya and Wakasagihime are familiar with each other.
Also I like how this isn't full-on bullying Reisen, which is annoyingly common with doujins focusing on Eientei.