I've been reading this excellent book on nationalism in modern Japan, and it's rather clear once focused and thinking about all the implications. But the topic of the first assemblies in a somewhat democratic Japan came up and it's got me a bit confused. Aside from the structures varying, the differences look very subtle (at least from what I've seen).
The overall changes of the era must have been difficult to understand for the japanese people, but how much were they concerned with the establishment of assemblies or democratic structures?
I cannot answer the question in its entirety, but here are discrepancies I identify.
How great were the differences between the Giseikan, Kōgisho, and Shugiin?
The problem is that “Giseikan” (議政官) and “Kōgisho” (公議所) were samurai from each domain. They were not democratically elected as far as I can tell since each domain sent a representative from the daimyo. The two were actually temporary assemblies existing only in 1869/70. They were absorbed into the executive.
“Shugiin” 衆議院 is from the Meiji Constitution written much later, circa 1877. So voting rights were very limited to the land owning class. It was initially only a small fraction of the populace that was able to vote. Later on, voting rights were expanded in the early 20th century due to labor tensions in the economy.