OK, so for people who think Shizuko's proposal is "democratic" (including Shizuko herself), you're misunderstanding political theory. What Shizuko is proposing is basic rule of law, which the Qin State actually pioneered under the Laws of Shang Yang. The problem with the implementation of this concept is that it was extremely harsh in the Chinese context and many elites in later dynasties managed to escape it. It really only worked under Shang Yang himself, who was able to implement it to the point of mutilating the nose of Prince Qian, Duke Xiao's ELDER brother and foremost military commander of the Qin State, as punishment for failing to educate the Crown Prince correctly.
Japan is actually very familiar with this concept, having learned Legalism in the Tang era. In fact, there was a very famous political experiment done by Takeda Shingen himself where he implemented the very harsh but unfair legalism under the Qin Dynasty of Shihuangdi on one of his conquered territories, but applied a much fairer and slightly less harsh legalism on another. The latter is basically what would have happened if Akechi had agreed to implement Shizuko's proposal. The result of Takeda's experiment was constant rebellion in the harsh implementation area but strong loyalty in the region with fair implementation. Shingen unfortunately died before being able to implement whatever his conclusion had been in the rest of his territories, and Katsuyori never had enough power to do so despite making several attempts. The Takeda were as much pioneers in radical Japanese governance principles as the Oda were, and in fact many of their ideas were "borrowed" later by the Tokugawa, who would employ many former Takeda loyalists.
Also, this manga seems to portray Akechi more like Ishida Mitsunari, in particular making him much younger than he should have been (the historical Akechi Mitsuhide was a tutor to Konoe Sakihisa, and Sakihisa was two years older than Nobunaga).