There you go, Hidaritsuu is now making Touhou arranges too, thus joining the likes of Demetori, CROW'SCLAW, Iron Attack and MyonMyon in the metal genre. This one features Rin. Very apt, considering Rumia looks like her. It's the Touhou character that most resembles her at any rate.
As far as crossovers go, these two are a classic. A tried and true formula, really. It was just a matter of time until it happened on Vocallective.