While popular in the US, apparently only one institution in Japan has moved to Google Apps to carry much of its IT services burden. That is Waseda University, a top private university in Tokyo and one that is at the center of Google's Android OS development for Japan.
To see why Google recommends Google Apps for institutions, see:
Top 10 reasons to use Google Apps
>> 1. Students will love you for it
Schools tells us that when they ask their students what email they'd prefer, they overwhelmingly say Gmail.
"Our students approached us about a year ago, saying that we needed to improve our email and collaboration services. We actually had our student government tell us, 'we want you to implement Google Apps.'" - Wendy Woodward, Director of Technology Support Services, Northwestern University
2. Free up your IT
Focus your IT on activities that add value instead of worrying about the uptime of your email services.
"Google Apps has allowed us to get out of providing these commodity type services - such as maintaining an email and calendaring system - and focus on the things that we are uniquely equipped to do, like providing more resources to be able to better support teaching, learning and research." - Todd Sutton, Assistant Vice Chancellor for Application Services, UNC Greensboro
3. Easy to deploy
No software to install, no hardware to buy, just validate your MX records and create your accounts to get started. To integrate with what you already have, we work with open standards, have created a multitude of APIs, can point you to open source solutions for common integrations, and have approved partners with experience deploying Apps in schools. <<
See link above for all 10 reasons.