Optimizing for Human-vs-Japanese AI

[Dereck]

In a previous post I asked whether anyone had ever built a pure Human‑vs‑Japanese AI scenario. The answer was essentially: “Not really.”

With the help of my Chief of Staff, we developed a plan to rebuild the Japanese naval OOB specifically for AI performance.

In the stock scenario we’re using as a base (Scenario 006 – December 8: The Full Campaign), the Japanese OOB includes 171 ships with a 9999 arrival date. These ships exist in the editor but never appear in the game. They formed the basis of a “hull budget” used to address long‑standing weaknesses in the Japanese AI while preserving historical flavor, early‑war scarcity, and overall scenario balance.

Guiding Principles

1. The AI does not perform optional conversions.
Any ship requiring a conversion bind would never be converted by the AI.
All Japanese conversion BINDS were removed.

2. The AI does reliably perform upgrades.
Upgrade chains were preserved exactly as‑is to maintain mechanical stability and ensure the AI benefits from historically appropriate improvements.

3. Only unused 9999‑hulls were repurposed.
No existing ships were overwritten or duplicated.
Only ships absent from the scenario were reassigned to new roles.

This avoids altering the historical OOB while giving the AI the logistical backbone it needs.

Why These Changes Were Necessary

The Japanese AI has several structural weaknesses caused by limited auxiliary capacity:
- It frequently fails to rearm destroyers and cruisers at forward bases
- It loses key auxiliaries early and cannot replace them
- It struggles to maintain logistics once the perimeter expands
- And unlike a human player, it cannot perform optional conversions

At the same time, the AI has notable strengths:
- It moves fuel and supply efficiently
- It builds bases aggressively
- It routes convoys competently
- It uses upgrade chains correctly

The goal is not to give Japan an advantage — only to give the AI the minimum logistical backbone required to behave like a competent opponent.

Repurposing Summary

Of the 171 unused 9999‑ships, the following new hulls were added:
- AG – 9
- AKE – 29
- DD – 10
- E – 16
- PB – 15
- PC – 36
- SC – 50
- xAK – 6

Doctrine Summaries

AG – Miscellaneous Auxiliary (9 hulls)
AGs reinforce supply distribution, forward sustainment, and general auxiliary duties.
All arrivals begin in 1942 to avoid inflating the early‑war support fleet.

AGP – MTB Tender (0 hulls)
The AI does not use MTBs in a way that benefits from tenders.
No AGP classes receive 9999‑hulls.

AKE – Ammunition Transport (29 hulls)
Strengthens the AI’s ability to rearm destroyers and cruisers, especially torpedo units.
Large AKEs receive most of the hulls; special‑purpose ships (Kashino, Mamiya, Irako) remain essentially unique.

DD – Destroyers (10 hulls)
Reinforces mid‑ and late‑war screening capability without altering early‑war balance.
Arrivals mirror historical construction tempo (1942–1945).

E – Escorts (16 hulls)
All reinforcements go to the Kaibokan families — the only escorts with meaningful ASW capability.
Arrivals restricted to 1943–1945 to match historical mass‑production tempo.

PC – Patrol Craft (36 hulls)
Adds Momi‑class hulls to strengthen mid‑war ASW coverage.
Arrive one per month from 1/42 through 12/44, providing steady reinforcement.

PB – Patrol Boats (15 hulls)
Reinforces early‑ and mid‑war coastal security.
PBs are not escorts; they provide harbor defense, picket duty, and absorb attrition.
Arrivals begin in 1942.

SC – Subchasers (50 hulls)
Reinforces the coastal ASW network.
SCs are short‑range, high‑attrition craft used for chokepoints, harbors, and convoy staging areas.
Distributed proportionally across all four SC families.
No SC arrives before 1942.

xAK – Cargo Ships (6 hulls)
Light reinforcement of the merchant fleet to support resource and supply movement.
Arrivals begin in 1942 to avoid inflating the 1941 opening.

Arrival Locations
- Destroyers and AKEs arrive at Tokyo
- All other ships arrive evenly at Sasebo or Maizuru