Methodology

Data sources

Candidate records are compiled from Japan Ministry of Internal Affairs and Communications (MIC) public election records, the mySociety EveryPolitician dataset for historical Shūgiin members, and the localgovjp open dataset of Japanese local government entities for prefecture and district metadata.

Metric definitions

Votes

Total ballots cast for the candidate in the listed election year and district.

Vote share

Votes as a percent of all ballots cast in that single-member district.

Rank

Position within the same district and election year, sorted by votes descending.

Outcome

“Won” if the candidate took the seat; “Lost” otherwise.

Incumbent status

Recorded entry status: incumbent, former, or newcomer.

Endorsement

Other parties that publicly endorsed the candidate as recorded in source materials.

Processing

• Raw source CSV is imported verbatim — no values are altered.
• Japanese party abbreviations are mapped to a stable English short label (LDP, CDP, JCP, etc.) for display only; the original Japanese name is preserved on every record.
• Ranks and district summaries are computed by deterministic SQL — same input always produces the same output.
• Posts are regenerated whenever the source CSV checksum changes.

Update cadence

The source CSV is checked on a periodic schedule. Each post displays the last-updated date in its header.