Hi saito_y,
thanks a lot for your help. I’m very sorry for this issue. Thanks to your screenshots I think we identified the problem: our calculations that setup the stereoscopic rendering area in UE4 are not matching what the Google Cardboard SDK is expecting on your device. If ok for you, we would need your email address to send you a version of the plugin with a tentative fix, so we can try to solve this issue quickly. You can write us at support@unamedia.com . Thanks again for your help!