TRUSTBANK uses AI agents to personalize Furusato Nozei gifts

TRUSTBANK partnered with Recursive to build Choice AI using OpenAI models, enabling personalized conversational recommendations that simplify Furusato Nozei gift discovery.

OpenAI Team
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Overview

TRUSTBANK partnered with Recursive to build Choice AI, a multi-agent AI system powered by OpenAI's GPT-4.1 series, to help users navigate Japan's Furusato Nozei (hometown tax donation) program. The system uses a routing model with specialized agents (Search, Recommendation, and Greeting) to provide personalized gift recommendations from a catalog of roughly 760,000 thank-you gifts, resulting in higher conversion rates compared to standard search.

What You'll Learn

1

How to design a multi-agent architecture with routing, specialized agents, and subagents for personalized recommendations

2

How to introduce controlled randomness in search results to promote fairness and regional diversity

3

How to dynamically switch between AI model sizes (nano, mini, full) based on latency and accuracy requirements

4

Why analyzing real user behavior patterns leads to better AI-driven product recommendations

5

How to structure a partnership between a domain expert company and an AI specialist for building conversational AI

Prerequisites & Requirements

  • Basic understanding of AI/ML concepts including LLMs and conversational AI
  • Familiarity with multi-agent system architectures and agent orchestration patterns
  • Understanding of RAG (Retrieval-Augmented Generation) systems(optional)
  • Basic understanding of recommendation systems and personalization techniques(optional)

Key Questions Answered

How does TRUSTBANK's Choice AI use a multi-agent architecture for personalized recommendations?
Choice AI uses a routing model that analyzes user input to determine intent (product search, recommendation, or greeting) and delegates to specialized agents. The Search Agent uses an SQL Query Agent to query the product database, the Recommendation Agent leverages user purchase and search history for personalized suggestions, and the Greeting Agent handles casual interactions. Each agent can invoke subagents and tools for orchestration, with final reranking by GPT-4.1.
What OpenAI models does Choice AI use and how are they selected?
Choice AI runs on the GPT-4.1 series, using GPT-4.1 mini as the default model for intent detection, search, and recommendations. The team experiments with dynamically switching between GPT-4.1 nano (for simple tasks like greetings), GPT-4.1 mini (for routing and search), and the full GPT-4.1 model (for final reranking and recommendations) based on latency and accuracy requirements during testing.
How does Choice AI avoid bias toward popular municipalities in Furusato Nozei recommendations?
Choice AI introduces controlled randomness into search results and varies recommendations across prefectures based on donation data to support fairness and regional diversity. Unless users clearly indicate specific preferences, the system intentionally surfaces smaller municipalities and niche products. This approach helps distribute donations more broadly rather than concentrating on already popular areas.
What is Furusato Nozei and why is it difficult to navigate?
Furusato Nozei is Japan's hometown tax donation program that allows taxpayers to redirect a portion of their taxes to municipalities they want to support, receiving thank-you gifts (local specialty products) in return. It's difficult to navigate because of the sheer number of participating municipalities and the enormous catalog of options—Furusato Choice alone lists roughly 760,000 thank-you gifts, making it challenging for donors to find the best options for their donation limit.
How did TRUSTBANK and Recursive collaborate to build Choice AI?
Recursive provided technical support from the planning stage, designed and implemented the conversational AI agent, and built the RAG system. TRUSTBANK prepared the thank-you gift database, defined functional requirements, and integrated the features into their Furusato Choice app. TRUSTBANK chose Recursive as a partner due to their advanced AI expertise and global experience, as TRUSTBANK lacked internal developers specializing in AI.
How does Choice AI handle different user types and interaction patterns?
Choice AI dynamically generates prompts based on user-specific information, routing existing users through one interaction path and first-time users through another. Analysis revealed many users interact similarly to search engines, providing extensive product information and expecting immediate recommendations. Based on these findings, the team adjusted the recommendation flow to surface suggestions earlier and expanded the variety of recommended products.
What results did TRUSTBANK achieve with Choice AI compared to standard search?
Users who used Choice AI saw higher conversion rates than those who relied on standard on-site search. The AI was effective because it could draw out vague needs—like preferences and budget—that users themselves often struggled to articulate, and could recommend specific thank-you gifts. The conversational approach allowed even vague requests like 'a gift for my parents' to surface suitable recommendations.

Key Statistics & Figures

Thank-you gifts listed on Furusato Choice
~760,000
Size of the product catalog that Choice AI helps users navigate

Technologies & Tools

AI/ML Model
Gpt-4.1
Final reranking and recommendation generation in the multi-agent pipeline
AI/ML Model
Gpt-4.1 Mini
Default model for user intent detection, search agent, recommendation agent, and SQL query generation
AI/ML Model
Gpt-4.1 Nano
Lightweight model used for simple tasks like greeting agent responses
API
Openai API
Foundation for building the Choice AI conversational recommendation system
AI Architecture Pattern
Rag
Retrieval-Augmented Generation system built by Recursive for querying the thank-you gift database
Query Language
SQL
SQL Query Agent generates database queries to search the product database

Key Actionable Insights

1
Design multi-agent systems with a routing layer that delegates to specialized agents based on user intent. TRUSTBANK's architecture uses a routing model for intent detection, then delegates to Search, Recommendation, or Greeting agents, each capable of invoking subagents and tools. This separation of concerns enables each agent to be optimized independently.
This pattern is especially effective when user queries span multiple distinct intent categories (search vs. recommendation vs. general conversation) that require different processing pipelines and data sources.
2
Use different AI model sizes strategically within the same system to optimize for cost, latency, and accuracy. TRUSTBANK uses GPT-4.1 mini as the default but experiments with dynamically switching to nano for simple tasks and the full model for complex reranking. This tiered approach allows you to allocate computational resources where they matter most.
Apply this when building production AI systems where latency and cost are constraints. Simple tasks like greeting detection don't need the largest model, while final recommendation quality benefits from more capable models.
3
Introduce controlled randomness in recommendation results to promote fairness and diversity, rather than always optimizing for popularity or relevance alone. TRUSTBANK varies recommendations across regions based on donation data to prevent concentration on a small set of popular items, helping users discover smaller municipalities and niche products.
This approach is valuable for any marketplace or recommendation platform where you want to balance user satisfaction with fair distribution across suppliers, regions, or lesser-known options.
4
Analyze real user interaction patterns after deployment to refine your AI system. TRUSTBANK discovered that users often treated their conversational AI like a search engine, providing extensive product information and expecting immediate results. This led them to adjust the recommendation flow to surface suggestions earlier.
Users rarely interact with AI systems the way designers expect. Post-launch behavioral analysis is essential to understanding actual usage patterns and iterating on the conversational flow accordingly.
5
Dynamically generate prompts based on user-specific context rather than using static prompts for all users. Choice AI combines agents differently for existing users versus first-time users, creating personalized interaction paths that adapt to the user's history and experience level with the platform.
This is particularly effective for platforms with diverse user segments where a one-size-fits-all conversational experience would fail to address the different needs and knowledge levels of various user types.
6
When your organization lacks internal AI expertise, partner with a specialized AI firm while maintaining clear division of responsibilities—domain expertise and data preparation internally, AI architecture and implementation externally. TRUSTBANK handled the gift database and functional requirements while Recursive built the conversational AI and RAG system.
This collaboration model works well when the domain knowledge (product catalogs, user behavior, business rules) is complex and company-specific, while the AI engineering can be externally sourced from specialists.

Common Pitfalls

1
Using static, one-size-fits-all prompts for all users regardless of their experience level or history with the platform. Choice AI found that existing users and first-time users need fundamentally different interaction paths, and dynamically generating prompts based on user context significantly improves personalization.
Design your prompt templates to accept user context variables from the start, making it easier to create differentiated experiences for different user segments.
2
Optimizing recommendations purely for relevance or popularity, which concentrates results on a small set of well-known items or providers. TRUSTBANK found this created bias toward specific municipalities, undermining the program's goal of supporting diverse local communities.
Consider incorporating controlled randomness and diversity constraints into your recommendation algorithms to ensure fair distribution, especially in marketplace-style platforms.
3
Assuming users will interact with conversational AI in a conversational manner. TRUSTBANK's analysis revealed many users treated the AI like a search engine, providing extensive product details and expecting immediate results rather than engaging in multi-turn dialogue.
Build your conversational AI to handle both search-like queries and genuine conversations, and adjust the flow to surface results earlier when users exhibit search-engine-style behavior.
4
Using the same large AI model for all tasks in a multi-agent system, leading to unnecessary latency and cost for simple operations. Simple tasks like greeting detection can be handled by smaller, faster models while reserving more capable models for complex reasoning tasks.
Profile your agent tasks by complexity and match model size accordingly—nano for simple classification, mini for standard operations, and full models for complex reasoning and reranking.

Related Concepts

Multi-agent AI Architecture
Conversational AI
Rag (retrieval-augmented Generation)
Recommendation Systems
Intent Detection And Routing
Dynamic Prompt Generation
AI Model Size Optimization
Controlled Randomness In Search Results
Fairness In Recommendation Algorithms
Ai-powered E-commerce Personalization
SQL Query Generation With Llms
User Behavior Analysis For AI Systems