Numbering for serieses with negative-numbered volumes like TWINTAIL cannot be done adequately as things currently stand, where 0 is as low as you can go.
Is this something like where the prequel series starts at a random chapter number and counts backwards till it hits "chapter zero", which is when the original series starts?
Is this something like where the prequel series starts at a random chapter number and counts backwards till it hits "chapter zero", which is when the original series starts?
