---
title: "Kouichi Hayashi — Publisher Overview"
type: publisher
publisher: "Kouichi Hayashi"
publisher_slug: "kouichi-hayashi"
canonical_url: "https://marlvel.ai/publishers/kouichi-hayashi"
last_updated: 2026-04-28T07:46:50.946Z
source: Marlvel.ai
license: CC-BY-NC-4.0
citation: "Marlvel.ai — Kouichi Hayashi Publisher Overview"
---
## ⚠ Content Warning

This publisher's portfolio includes apps classified as sensitive (gambling). Information is aggregated from public sources for informational purposes only. Information is provided for context only and is not professional advice.

---

# Kouichi Hayashi — Publisher Overview

> Preserving a niche portfolio of 3D hobby simulations and traditional Japanese card games for a dedicated enthusiast community.

- **Publisher:** Kouichi Hayashi
- **Website:** [https://googolplex.jp](https://googolplex.jp)
- **Headquarters:** Musashino-shi, Tokyo, Japan
- **Founded:** 2025
- **Employees:** 1-10
- **Overview generated:** 2026-04-28
- **License:** CC-BY-NC 4.0

## Executive summary

Kouichi Hayashi operates as a solo developer entity specifically structured to provide long-term support for a legacy portfolio transitioned from Googolplex Ltd. The publisher maintains a distinct moat within the 3D 'toy' simulation niche, prioritizing functional continuity for a dedicated hobbyist base over aggressive user acquisition. This transition to a personal business model signals a strategic shift toward portfolio preservation and maintenance rather than new product development.

## Publisher DNA

- **Primary focus:** 3D hobby simulations and traditional card games
- **Scale:** studio
- **Target audience:** Hobbyists interested in model railroading and casual gamers seeking physics-based simulations or traditional Japanese Hanafuda.
- **Origin:** Established in 2025 as a personal business to take over and support applications previously managed by Googolplex Ltd.

## Portfolio momentum

- **Velocity:** maintenance
- **Active apps:** 12
- **Abandoned apps:** 0

With zero new releases in the last six months, the publisher is currently focused on the maintenance and support of its existing 12 active titles.

## Aggregated portfolio metrics

- **Total reviews (all apps):** 2,665
- **Weighted rating:** 3.88 / 5
- **Apps in portfolio:** 16

## Category breakdown

| Category | Apps | Share |
| :--- | :--- | :--- |
| Games | 13 | 81.3% |
| Utilities | 2 | 12.5% |
| Photo & Video | 1 | 6.3% |

## Top apps

- **googolChooChoo3D** — Portfolio flagship — 1,113 reviews and a 4.07 rating.
- **Toy Boxing 3D** — Highest-rated major title — 4.11 stars across 469 reviews.
- **Toy Train 3D** — Core hobbyist simulation — 349 reviews and a 3.89 rating.
- **Koikoi Lite** — Traditional card game niche — 204 reviews with a freemium model.

## Signature patterns

- Heavy emphasis on 3D 'Toy' themed simulations including trains and rollercoasters
- Monetization primarily through free-to-play models with ad-supported 'Lite' versions
- Consistent use of physics-based mechanics and 3D visualization tools
- Portfolio consists largely of legacy titles originally released between 2013 and 2017

## Bottom line

Kouichi Hayashi is a well-defined maintenance studio focused on the long-tail stability of its simulation catalog. The publisher's transition to a solo-operator model suggests a low-overhead strategy aimed at sustaining existing niche market fit.

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© 2026 Marlvel.ai | [Publisher apps index](https://marlvel.ai/api/llm/publishers/kouichi-hayashi) | [Methodology](https://marlvel.ai/api/llm/methodology)
Data licensed under CC-BY-NC 4.0.

---
© 2026 Marlvel.ai | [Full publisher profile](https://marlvel.ai/publishers/kouichi-hayashi) | [Publisher apps index](https://marlvel.ai/api/llm/publishers/kouichi-hayashi) | [Methodology](https://marlvel.ai/api/llm/methodology)
Data licensed under CC-BY-NC 4.0.