Can I rent a Pocket Wifi in Japan ?

The Pocket Wifi can be delivered to your hotel in Japan or pick up at the following list of japan airports.
Then Yes, as you can book the Pocket Wifi on line, you can order a Pocket wifi in Japan. Please note that the necessary time between order and delivery is 5 days.

About the final information regarding the pickup counter, you will be contacted 2 days before the starting date of your rental, along with your tracking number.

List of pick up airports : Narita Airport, Haneda Airport, Kansai Airport, Chubu Central Airport, New Chitose Airport and Fukuoka Airport