D is the "girl" who talked with Kumoko using a smartphone. She created the System, so she has root access, and can write and compile new code, like she did with Wisdom. Sariel is also an Administrator, she provides the Divine Voice / Voice of Heaven (temp), like a telemarketer mindlessly reading out a script 😁. D is actually one of the strongest gods in the Kumo Desu ga universe, but she's lazy, so she pretends to be "Wakaba Hiiro", a high school student in Japan, just to hide and get out of work. When the attack (targeting her) exploded in the classroom, she reincarnated the students into the System, supposedly because she felt responsible. But, just for fun and kicks, and partly to throw other gods off her trail, she put an altered version of her memories as "Wakaba Hiiro" into a spider that was also killed by the explosion in the classroom, and unintentionally a tiny portion of her soul. That portion of soul was so small it was no more than a shed hair or flake of skin for her, but compared to a spider's soul, that portion of a god's soul is huge. That contributed to Kumoko's success, but it was still mostly due to Kumoko's efforts (according to D).