To my knowledge, it was common to have large shields deployed during battle by dedicated troops but these were large and meant to be driven into the ground more like an emplacement we see in siege work. Other than that there have only been a handful of examples of Japanese soldiers using shields in periods such as the Sengoku Jidai from what I have found.

What are the reasons for this? Was it doctrinal or was it part of the martial culture of the period?