Budget stress usually comes from ignoring the big three: transport, lodging, and the activity ticket (lift / boat / rental / campsite).

Lock these first

1. Flights or long-distance rail.
2. Base lodging near your JPFun shortlist.
3. Lift pass, dive boat, board rental, or camp booking.

Flexible bucket

• Meals (mix konbini + one nice bowl).
• Onsen day baths.
• Souvenirs.

Activity ranges (rough mental model)

• Ski: passes + rental dominate; powder towns cost more on weekends.
• Scuba: boats are the line item; do not cheap out on operators.
• Surf: transit + rental; lodging can be hostels.
• Camp: site fees look small until parking, gear, and food add up.

Leave a 10–15% buffer for weather pivots (extra night, taxi, second boat attempt). That buffer is cheaper than a ruined mood.