Kikou Sennyo Rouran

Both are written by Sho Aikawa, and are very thematically similar - a fight for Japan, corruption in the higher echelons of society, a country destroying itself from within - and even have suspiciously similarly named military organisations with somewhat questionable ethics. Aikawa's writing style is distinct, and the shows carry a very similar atmosphere and pace, as well as being 15 minutes an episode. Ranga is far, far superior to Rouran, however.