We here at Degica Games would like to apologize for all of the users effected by the current issue with the "Koihime Enbu" soundtrack not properly downloading to their Steam accounts.
We are currently working on resolving the issue and humbly ask for your patience during this process.
As soon as a solution is found, we will be sure to inform you all first thing!
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UPDATE
We have found and implemented a solution to the issue of the Koihime Enbu soundtrack not properly downloading.
The soundtrack now should correctly download for users who have purchased it.
If any users are still having issues please do let us know through our support email address.