A "truth-seeking method" of Kuukai and the Shingon school of Buddhism from the Mahavairocana Sutra:

"a ji" = "the word a", which is the basic essence of all things
"kan" = "to see" with one's mind/heart

Ajikan is a form of meditation upon the symble a, which holds that the beginning of all things is in the heart and mind, and one must concentrate on this to understand how any idea one holds can change the shape of the seen and unseen worlds.