tochi-satei-kun is an Apache-2.0 local-first OSS tool for preliminary Japanese land brokerage valuation support. It runs locally, uses white-box hedonic regression and comparable transaction analysis, and generates Excel and JSON outputs from user-provided property, MLIT transaction, and L01 land-price-publication files. The tool itself does not send input files to external services. Outputs are not real-estate appraisal opinions; users must separately verify site conditions, legal restrictions, rights, and other material facts, and the final decision remains with the user.