I'm going to change all instances of "North Mk. II" to "#2" because...
His original name is Norusu Ni-gou. Accepting that that's supposed to be "North" rather than "Norse", "Ni-gou" does not imply an improvement over another model as "Mark #" does, and is pretty universally translated as #2. (This "gou" usually signifies a thing in a similar, even identical, series of non-living things. Think "The first X", "The second X", etc.)
Besides that, I've just assumed that North #2 is guilt-wracked over the war and refuses to change his name or body until he can become something other than a war machine in a line of war machines. (Montblanc, by contrast, succeeded in this regard.)
I'm going to change all instances of "North Mk. II" to "#2" because...
His original name is Norusu Ni-gou. Accepting that that's supposed to be "North" rather than "Norse", "Ni-gou" does not imply an improvement over another model as "Mark #" does, and is pretty universally translated as #2. (This "gou" usually signifies a thing in a similar, even identical, series of non-living things. Think "The first X", "The second X", etc.)
Besides that, I've just assumed that North #2 is guilt-wracked over the war and refuses to change his name or body until he can become something other than a war machine in a line of war machines. (Montblanc, by contrast, succeeded in this regard.)