Operation Storm by John J. Geoghegan is a great book! It is about the I-400 class submarines of the Imperial Japanese Navy and their secret missions. These submarines were designed to carry aircraft and were intended to attack targets as diverse as New York City and the Panama Canal.
This book is told in a very personal style, discussing individual sailors, the construction and operations of the incredible weapons systems. The research is great, there was much here and I had not read before.