The Story of Kiryuu Ren's Past:

This story takes place in Zero Dimension's Gamindustri where it was invaded by the Dark CPUs
The Goddesses tried to put a stop to them but they're not strong enough to match their strength, being left helpless and powerless to stop the Dark CPUs, defeated by them

After her son, Kiryuu Ren ( the author which is me, ofc), witnessed the death of all the CPUs including Green Heart, his mother, he's filled with nothing but despair, rage and hatred for the Dark CPUs, swearing his oath to hunt them down once and for all, but couldn't do it alone, but to seek help from his comrades in order to combine their strength with him to defeat them