[FiverMaki]

Please confirm this pull request meets the following requirements:

• I followed the contributing guidelines: https://github.com/github/explore/blob/main/CONTRIBUTING.md.
• This change is not self-promotion.

Which change are you proposing?

• Suggesting edits to an existing topic or collection
• Curating a new topic or collection
• Something that does not neatly fit into the binary options above

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Curating a new topic or collection

• I've formatted my changes as a new folder directory, named for the topic or collection as it appears in the URL on GitHub (e.g. https://github.com/topics/[NAME] or https://github.com/collections/[NAME])
• My folder contains a *.png image (if applicable) and index.md
• All required fields in my index.md conform to the Style Guide and API docs: https://github.com/github/explore/tree/main/docs

There are already many "Made in" collections (China, Korea, Taiwan, Singapore, and others), but there is no Made in Japan collection yet. This adds one, starting with Ruby, which was created in Japan by Yukihiro Matsumoto. I've kept the initial list small so that others can add more projects from Japan over time.

[github-actions]

Maintainer triage

Collection made-in-japan

Item	Stars	Last push	Owner type	Notes
ruby/ruby	23,797	2026-11-03	Organization	–