A web based, client-side extractor that allows for easy extracting and editing of Astral Chain's files. It also includes a Quest Editor for editing cases and other game data, with full support for task editing. Supports many file types, including model previews (WMB)- However, for model editing, use AstralChain2Blender and Blender2AstralChain.
You don't need to download anything to get it working- just open it in your modern-ish browser.