When staying in a shingon temple atop of Mt, Koyusan I had the opportunity to be guided through this graveyard and led through the Ajikan Moon Disc Meditation. Shingon meditation activates visual references such as mandalas by empowering them with mantras to harmonize the voice mind with the visual embodiment.
The Ajikan meditation consists of approaching an image of the moon and performing three prostrations followed by sitting and viewing the moon with a relaxed gaze. One than can chant "Ah Vi Ra Un Ka" 100 times to stimulate the cakra body. Following this should follow 100 homage mantras to ones guru or god and than begin chanting the seed syllable "Ah"Ah is the empty, free, eternal ah-ha. After a short period the meditator closes their eyes and continues to envision the moon in their internal vision, opening their eyes as much as one needs until able to sustain the vision.
Transforming the disc into a tiny sphere, we take the sphere into our heart center and begin breathing into it as it slowly begins to encompass all of our organs and eventually our bodies. Than allowing the ball to encompass our neighbors without judgements, we continue then to expand to the size of our building, city, state and eventually the entire world, moon, stars, galaxies until all is one within. Exit the meditation with a rapid reverse and don't forget your final prostrations!
Want more? Here's a link to a mandala of the Shingon cosmology!
And here's art on the Bardo Thodol or Land of the Dead
And the lord of the dead