Looks to be standard Digicode. Which is a letter substitution for one of Japan's alphabets. Not a clue which, though. There is a version that aligns with the Latin Alphabet, but it isn't nearly as pretty.
As for the style of Holy Ring, it looks to be most closely based on the Tailmon/Gatomon design.
Looks to be standard Digicode. Which is a letter substitution for one of Japan's alphabets. Not a cl