What the calculator uses
Each non-final stop creates a rail leg on the departure date you enter. The final destination does not require an unused date.
Each supported leg must have a current explicit fare quote. The optimizer then compares individual tickets with eligible pass activation windows and mixed ticket-and-pass combinations.
The planner covers all Shinkansen stations nationwide plus major conventional JR limited express routes. If a route is not yet source-backed, it clearly blocks the result instead of estimating.