I have converted my application into MultiDex to bear with 64k dex limit. Now it looks like this:
public class App extends MultiDexApplication {
private App
I've finally solved it! Cause was not in the onCreate() method. There was this line from logcat that gained my attention:
I/dalvikvm﹕ Failed resolving Lcom/playday/app/core/AppWrapper; interface 8940 'Lretrofit/ErrorHandler;'
W/dalvikvm﹕ Link of class 'Lcom/playday/app/core/AppWrapper;' failed
This line fired before all the MultiDex log. Source of the problem was Retrofit ErrorHandler interface, which AppWrapper implements.
As @AlexLipov said in his answer, Dalvik just couldn't find ErrorHandler class and failed to load AppWrapper.
Anyway, solution is not to implement ErrorHandler directly by AppWrapper and pull it into private variable instead.