  We show that the ring of modular forms with characters for the even
unimodular lattice of signature (2,10) is generated by forms of weights 4, 10,
12, 16, 18, 22, 24, 28, 30, 36, 42, and 252 with one relation of weight 504.
The proof is based on the comparison of the orbifold quotient of the symmetric
domain with the root stack of the coarse moduli space.
