IMHO: a Shingon prier ...
In Vajrayana, Aizen Myoo is the irritated version of Vairocana, the great sun of wisdom...
Kokuzo bosatsu is also à great bodhisatva from vajrayana,
Seishi bosatsu is, with Amithaba, one of the 3 great saints of Ouest, from the "pure earth" (ground) buddhism.
The full moon and crescent moon is a direct allusion of Shigon doctrine of the "Shape of the mind (spirit)" being allways full moon even if showing crescent or hidden by clouds...
You often see this symbolic at Koya San...
Same for the habaki, beautifull by the way...
Best regards,
Eric