Thanks to everyone who already got themselves a copy or is planning to do! I hope you guys will have as much fun with the game as I had developing it.
A little info on the side:
It seems that Steam is currently not recognizing the language settings of your client for the game. Make sure to set your prefered language in the steam client settings:
1. Go to the library page of Idle Demon Summoner
2. Click on the gear icon or right click the game in entry in your list of games
3. Click on Preferences
4. Switch to your prefered language in the Generals Tab