2019 Japan Unified Local Elections(April) and Upper House elections (July 21st)

[Tintrlvr]

Not to sound like a conspiracy theorist, but I'm starting to wonder if there's some sort of unreported or inadequately-reported democratic backsliding on the level of voting rolls or freedom of the press or something going on in Japan. The repeated, clockwork-like LDP landslides at practically every level no matter what the Abe government is doing or has done lately are starting to get downright unsettling.

I think this has to do with Japanese Culture and Asian Values that value stability and continuity and shuns anything new/populist as well as a traditional bent towards conservatism/nationalism. Maybe our Chinese friend can give us more insight into that. Important to Remember that Japan never elected a Opposition Government until 1993.
Also Japanese still vividly remember the DPJ Government from 2009-2012 which, justifiably or not, is blamed for incompetence and economic mismanagement. So i think the reason why Japan is stubbornly refusing change, is not due to democratic backsliding but rather the lack of a convincing alternative.

It's way overstating this to call it "Asian values", btw. South Korea and Taiwan show clearly that other East Asian cultures, when in a democracy, have no compunction about throwing out the governing party. This would also be true if mainland China were a democracy. It's Japan specifically that has a very tradition-bound, hierarchical society that makes changes of power through democracy difficult and a permanent displacement of the "party of government" especially difficult. (The DPJ had the really bad luck of peaking right as the recession was taking hold, though.)

[Tintrlvr]

I can understand why DPP wouldn’t want to merge, but why are SDP and CDP still individual parties?

SDP has a long history as an independent party (it was never part of the DPJ), so it's not surprising that they wouldn't automatically want to merge.

As I understand it, the SDP is also sometimes to the left of even the JCP on some issues, so there is at least as much ideological space between the CDP and the SDP as there is between the CDP and the DPP.