TLDR: They demoed a direct retinal projection display with a thin, transparent mirror embedded in the lens, enabling glasses that look more like everyday eyewear while reducing costs compared with waveguide-based designs.

This Japanese article has a few more details: https://www.watch.impress.co.jp/docs/news/2145266.html

This picture (with English text) has a bit of the detail showing their reflector structure, which is also in one of the pictures of your Japanese page:

https://www.tdk.com/system/files/featured_stories/features-o...