Happy Academic/Business New Year
April 1 is a big day in Japan. No joke. The school year begins in early April, and companies begin the fiscal year on April 1, with the new recruits all starting work on the same day. Busy, busy, busy!
Additionally, within companies, transfers and new postings take effect on April 1, so for the first few days of the month, the replacements scurry around introducing themselves within the company and to customers so everyone knows what's going on.
Another interesting side effect is that lots of these transferees are moving at the end of March, so there is just a ton of activity at this time of year.