How Japanese building budgets are structured

1. Shell works — 70–75% of total

This is the building itself: foundation, frame, roof, envelope, fit-out, and services. The per-tsubo headline covers only this layer.
Wood luxury: JPY 0.7–1.2M / tsubo.
RC luxury: JPY 1.2–1.8M / tsubo.

A 40-tsubo RC home runs JPY 48–72M on shell alone.

2. Ancillary works — 15–20% of total

Site work outside the building shell. Frequently missed by first-time owners:

• Ground improvement (when required): JPY 1–4M
• Exterior and landscaping: JPY 2–6M
• Demolition of existing buildings: JPY 1.5–4M
• Water, sewer, gas service lines: JPY 0.8–1.5M
• Temporary power, hoarding: JPY 0.5–1M

3. Soft costs — 10–15% of total

• Design & supervision fee: 8–12% of shell
• Permit and structural-review fees: JPY 0.2–0.8M
• Title registration and stamp duty: JPY 0.3–0.8M
• Real-estate acquisition tax, recurring property tax
• Fire and earthquake insurance: JPY 0.4–0.8M over 10 years

The per-tsubo trap

Ads that quote "from JPY 0.6M / tsubo" describe a stripped shell. Add the ancillary and soft layers and total cost lands around 1.3–1.4× the shell number. Always make decisions on all-in, tax-inclusive totals.

Worked example — 40-tsubo RC residence

Shell (JPY 1.5M × 40)	JPY 60M
Ancillary works	JPY 10M
Soft costs (incl. design)	JPY 9M
Total	~ JPY 79M

"Hiring an architect adds cost." Not quite — design and supervision are 8–12% of shell, and that fee almost always returns several percent in tighter contractor pricing.