The meaning of the Geki trident is "triumph over ignorance", so the plaque over the gate says that once passing through it, the guardian spirit will help you to become wise and virtuous.
EXIF info:
Nikon Df
Lens: VR 28-300mm F/3.5-5.6G
Focal Length: 28mm
Aperture: F/6.3
Shutter Speed: 1/640s
ISO Sensitivity: ISO 200