I don't think you're supposed to do this in karaoke bars:
But Kazuma is like Haruka's father, so... no, it's still probably not okay.
Yakuza Of the End's fifth download content includes this devil outfit for Haruka and some other goodies like smokes and stamina power ups. Look for the free download tomorrow.
Here's devil Haruka standing next to patriotic (if he were American instead of Japanese) Kiryu.