[Rance-mod] Japan Expanded & AI Overhaul

A Japan mod made by a Chinese player who probably drank too much. I like Japanese beer.

This mod adjusts and partly reworks several vanilla Japan routes to make the flow smoother, while adding decision systems, special units, Japanese doctrines, Officer Corps spirits, and a configurable challenge AI.

This mod is designed with all DLC enabled. Missing key DLC may cause errors or broken features.

• Rebalanced focus time, rewards, structure, and mutual exclusivity so the army, navy, and air force can develop more evenly.
• Reworked Japan’s MIOs (Military Industrial Organizations) with a more unified layout.
• Added two groups of Japanese special units and dedicated regimental support companies.
• Improved several advisors and zaibatsu company traits.
• Added route-specific Trade, Conscription, Economy, and Occupation Laws, plus faction charters for some factions.
• Added decision series for the Ministry of Colonial Affairs, Ministry of Munitions, Ministry of Commerce and Industry, and Imperial General Headquarters.
• The Imperial General Headquarters decisions provide strategic and landing operations, reduce island-hopping micromanagement, and use surprise-attack mechanics to break defenses.
• More strength control is available through custom game rules.

AI difficulty has six levels: Easy, Normal, Hard, Lunatic, Extra, and Phantasm. Phantasm is unfinished. The naming style is inspired by Touhou Project.

Difficulty mainly changes AI division templates and extra bonuses. Choose a level that fits your own skill and the other mods you use. Even with the default weakened values, this mod is still slightly stronger than vanilla Japan, so a pure vanilla challenge is not recommended; helper mods or other focus-tree expansion mods are better.

The AI’s economy management, frontline control, land/naval/air equipment designs, and division templates have been heavily improved, though flaws remain. I am happiest with the production-control and frontline-control systems, especially the multi-front settings. Modders interested in AI behavior are welcome to look at the code.

Not every route has a challenge-ready AI yet. Please check the route list below and select the matching route in custom rules. The historical route is not finished. Before challenging a route, try playing it yourself or watching an observe game, because the AI’s scripted strategy depends on its normal expansion flow.

The AI can also serve as a teammate. In completed routes, however, it will not actively join ally wars, so Japan can keep its preemptive-strike mechanics. Please wait for Japan to declare war by itself.

Completed:

• Lecture Group route, easter egg: Mao Zedong. This route was mainly made as nostalgia and in-jokes for Chinese players, so foreign players may find it strange.
• Kodoha route, easter egg: Kaguya.

Both completed routes join existing major factions, annex countries, and focus more on large Eurasian land wars. Future routes will add special subject and puppet mechanics.

Planned:

• Labor-Farmer Buddhist State route, easter egg: Byakuren Hijiri.
• Historical route, easter eggs: Daiteikoku characters.
• Democratic route, easter eggs undecided: Sanae Kochiya or the Yorigami Sisters.
• Rance route, a fully fictional new route.

To control balance and support some other mods, this mod uses its own gameplay environment. You may feel that industry is more abundant than in vanilla.

I am not familiar with foreign players’ usual mod setups, so the numbers may not always fit perfectly. With six difficulties and many custom rules, though, there should usually be a workable challenge setting.

General doctrines, mainly land doctrines, have been simplified and rebalanced to lower overall number inflation and keep major-power doctrine strength closer together.

For AI challenges, this mod’s AI is not compatible with most AI enhancement mods. Special compatibility currently exists only for Rookie’s MOD.

If you only want to play Japan yourself, it should work with most mods, except major design-system changes such as naval rework mods. Some functions may still be affected by other mods.

Anime-style content is one of my main motivations for making this mod. I do not plan to add a switch to hide it, even if it may affect immersion.

Because of my limited ability, localization and this mod description are translated with AI assistance. Please leave a comment if you have suggestions for better wording.

Numbers still need tuning. Balance is only considered for the default special rules and AI difficulty below Lunatic.

I have limited free time and development capacity, so testing is not extensive. Please report problems in the comments and I will fix them when possible.

Suggestions for special advisors, events, mechanics, or other ideas that improve immersion when playing Japan are welcome. Collaboration is welcome too.

Foreign mods are not yet included in the descriptor compatibility list. If you want initial compatibility with a mod, leave a comment; I can add basic descriptor compatibility, but cannot guarantee perfect results.

Development began in late 2025.