Heads up! You can purchase Mushihime-sama Futari Ver 1.5 Black Label from the US Marketplace and save 1,200 precious Japan region Microsoft Points for something else.
But, you might want to wait before doing that. The Black Label pack has a disruptive flash freezing bug. Cave is aware of the issue and posted a blog that they are investigating it.
Black Label adds extra features to Mushihime-sama Futari Ver 1.5 like god mode and Spiritual Larsa, a new last boss. While Cave sold Black Label packs as DLC for Mushihime-sama Futari Ver 1.5 and Deathsmiles, Espgaluda II includes Black Label on the disc.
Thanks to commenter Honorless for the info!