Where to start on paper Japanese light-cruiser designs

Where can a reader find information on unbuilt Japanese light-cruiser designs?

Concise Osprey-style Japanese light-cruiser studies were the best starting point because no strong comprehensive book was then available.

No strong comprehensive book on Japanese light-cruiser designs was available at the time of the stream. Shorter Japanese light-cruiser studies comparable to Osprey's Royal Navy volumes provided a practical entry point while better books were forthcoming. This was a limitation of the available literature and did not imply that proposed designs were absent.