We hope you're enjoying the Majogami demo! Unfortunately the video settings configuration is not quite implemented in the demo, but you can actually still change resolution and full screen/windowed modes.
The following keyboard commands can be used to change graphic modes:
F11: Full screen/windowed toggle
F10: Resolution toggle (changes from 1920x1080→1280x720→960x540→1920x1080→...etc.)
A full video settings menu will be available in the final release.