Are there areas in Japan that consistently vote for non LDP parties? If so, what are the reasons why?
Indeed - in the old days when Japanese politics was more ideological, were there places that always voted for the Socialist and Communist parties?
Looking at the elections since rejoining in 1970, here's Okinawa, with pro-LDP majorities in lime green.
1970 reunification election: 2 LDP, 1 JSP, 1 OPP (eventually merged into JCP), 1 OSMP
1972: Same as 1970
1976: 2 LDP, 1 JSP, 1 JCP, 1 K (back when K was anti-LDP)
1979: Same as 1976
1980: Same as 1976
1983: Same as 1976
1986: Same as 1976
1990: Same as 1976
1993: 2 LDP, 1 JSP, 1 JRP, 1 JCP
1996: 2 NFP, 1 SDP
2000: 1 LDP, 1 NKP, 1 SDP
2003: 2 LDP, 1 NKP, 1 SDP2005: 2 LDP, 1 SDP, 1 IND
2009: 2 DPJ, 1 SDP, 1 PNP
2012: 3 LDP, 1 SDP2014: 1 JCP, 1 PLP, 1 SDP, 1 IND
2017: 1 LDP, 1 JCP, 1 SDP, 1 IND
2021: 2 LDP, 1 JCP, 1 SDP
Only in the backlash year of 2012 did the LDP get an absolute majority on their own.