Today is White Day, March 14, the day that Japanese women (and women from other parts of Asia) get gifts of chocolate (originally marshmallows, then white chocolate, hence the White Day name) and other cool stuff from their significant other. This is a reciprocal gift based on gifts given a month before on Sei Baruntain, or Valentine's Day.
How do the Japanese prep for a Hanami? Firstly, they check websites that give predictions about when the cherry blossom bloom. A good one is maintained by JR, the Japan Railway. Then you contact your friends and colleagues and see who's up for a picnic. Then you go to your local 100 yen store -- think Daiso -- and get your stuff. The Japanese concept of mottenai applies here...why waste money when you're going to have to throw stuff away/recycle stuff anyway?
Lunar New Year is still considered a special time in Japan. Too much tradition is shared between Japan and China to just ignore this time of the year. So Japan has its Haru Matsuri, the Spring Festival, which begins every year around the beginning of February. Haru Matsuri starts with the observance of Setsubun.
Japanese summers are notorious for being hot and sticky. What better way to keep things cool than to organize an event where water and ice factor into almost everything? The Pokemon Company held their annual Pikachu Outbreak, featuring the most popular Pokemon character of all, and gave it a specifically nautical theme.
Long before the advent of air conditioning, which is pretty much ubiquitous in Japan, the Japanese people needed to learn to cope with their hot, sticky Summer climate. To that end, the whole period is liberally scattered with outdoor festivals. When it's too hot to sleep, you take your mind off of the misery by going to visit shrines, temples, and town squares, where street food, drink and dancing help make the hot season bearable. The traditions have held to this day.