April in Japan marks the start of a new school year. The city is filled with new students and new members of society, and there is an expectation that something will begin.
The cherry blossoms that bloom at the same time seem to celebrate this.
This comes from the fact that a legal reform in 1886 meant that the fiscal year began in April, and in Japan, where we have four seasons, people are surely happy to see the new school year begin with the arrival of spring.