VN Engine 2D

The developers describe how their game uses AI generated content like this:

Some Steam store graphical assets for VN Engine 2D, such as capsule and library artwork, may have been created with AI assistance and were manually reviewed before submission. VN Engine 2D is a desktop editor for creating 2D visual novels and interactive story projects. The Steam build does not include player-facing live AI generation, does not connect to external AI services during use, and does not require users to enter third-party API keys or pay for AI services outside of Steam.

Required on Steam store pages since 2024. It covers content that ships in the game, on its store page or in its marketing — Valve does not require a disclosure for AI tools used during development, so this says nothing either way about how the game was made. Check it on Steam.