Since Android 8 (Oreo) and higher, Google has restricted sideloading.
If you successfully install NejiSimNeet 05 but it won't run, try these fixes: NejiSimNeet 05 Android.apk
While official documentation is sparse (a common trait for indie doujin software), user reports and forum leaks suggest the following features for version 05: Since Android 8 (Oreo) and higher, Google has