Eighty-Five Kilometers Without Mercy
Four mountains. Eighty-five kilometers of asphalt linking them. No breaks. No shortcuts. The Big Four Endurance isn't about single-pass mastery — it's about sustained performance. Can your car maintain pace across mixed terrain? Can you maintain focus when kilometer 65 feels identical to kilometer 15 but your arms are heavier and brake fade is becoming real?
This curated route connects Gunma's four legendary peaks — Akina/Haruna, Akagi, Myogi, and Usui — in a continuous loop designed to test everything. Tight technical sections demand precision. High-speed straights require confidence. Elevation changes stress cooling systems. Surface transitions punish lazy suspension setup. Initial D showed individual battles on these mountains. Big Four shows you what happens when you string them together into a marathon.
The route is divided into four legs, each named after its mountain, each presenting different challenges. You start fresh at Akina. You finish exhausted at Usui. And between those bookends, you learn which components of your car — and your driving — were properly prepared and which were just optimistic.
The Four Legs
Leg 1: Akina Section (0-22km) — Technical wake-up call. The route begins with Akina's downhill — same 6km Initial D made famous — then transitions to connector roads threading through forest. Mixed radius corners, elevation drops, surfaces that shift from perfect asphalt to rough patch within single turn. This leg establishes baseline: how's your car handling? How's your focus? Mistakes here multiply across remaining 63 kilometers.
Leg 2: Akagi Section (22-45km) — Fast elevation. After Akina's technical warmup, Akagi delivers speed. Long straights between corners. Higher velocity entries. More committed braking zones. This is where cooling systems start working — brake temps rise, engine temps climb, tire pressures increase. If Akina tested technique, Akagi tests thermal management. Can your car handle sustained high load?
Leg 3: Myogi Section (45-63km) — Rhythm breaker. Just when you've settled into Akagi's pace, Myogi disrupts everything. Tight switchbacks. Rock walls on one side, drops on the other. No margin for error. No room to carry Akagi's momentum. You reset here — slower pace, sharper focus, accepting that kilometers 45-63 won't match the previous section's speed. This is mental endurance: adapting rather than forcing.
Leg 4: Usui Section (63-90 km) — The 184-curve finale. Usui Pass closes the loop with relentless corner density. 184 curves over 22 kilometers. Your arms are tired. Brake pads are glazing. Tires have heat cycles on them. And Usui demands you maintain precision through all 184 corners or crash trying. This isn't about setting records — it's about finishing clean. Completing Big Four means you proved durability, not just speed.
Route Specifications
Endurance philosophy: This route tests system durability — car and driver. Short sprints hide weaknesses. 90 km exposes everything: brake fade, tire degradation, cooling issues, driver fatigue, mental lapses. Completing Big Four clean (no offs, no mechanical failures) proves you understand automotive endurance, not just performance.
What This Route Teaches
Thermal management matters: Akina's 22km might not overheat your brakes. But 90 km of mixed elevation and braking zones? Everything gets hot. Brake fluid boils. Pads glaze. Rotors warp. Coolant temps spike. Big Four shows the difference between performance parts and race-grade components. The former work great for 20 minutes. The latter survive 4 hours.
Pace adaptation is skill: Fast drivers can maintain high pace on familiar roads. Smart drivers adapt pace to changing conditions. Leg 2's high-speed Akagi straights demand different mental calibration than Leg 3's technical Myogi rock sections. Forcing Akagi pace through Myogi equals guardrail contact. Learning when to push and when to recalibrate is what separates quick laps from clean marathons.
Car setup compromises emerge: Stiff suspension great for Akina's smooth downhill becomes punishing across Usui's rough patches. Aggressive brake pads perfect for single-run attacks fade by kilometer 70. Big Four forces you to choose: optimize for one section or compromise for all four? There's no perfect setup. Only trade-offs. Understanding which trade-offs you can live with is advanced driving education.
Waypoints Along the Route
1. Mount Haruna (Akina)
Leg 1 - Technical hairpins made famous by Initial D. The legendary 5 consecutive hairpins test precision.
→ View on Google Maps2. Mount Akagi
Leg 2 - High-speed straights and thermal management test. Home of the Akagi RedSuns.
→ View on Google Maps3. Mount Myogi
Leg 3 - Rhythm-breaking switchbacks with dramatic rocky peaks. NightKids territory.
→ View on Google Maps4. Usui Pass (Destination)
Leg 4 - The 184-curve finale. Each bend numbered. Impact Blue's home course.
→ View on Google Maps