A Perspective of the Weather
Definitely, I would say in May.
You can see Cherry Blossoms in the most part of Japan in April, however, you can still see cherry blossoms in the beginning of May if you visit Northern part of Japan, for instance, Niigata, Yamagata, Aomori, Hokkaido, etc.
I did not choose April because it is still cold (I am さむがり, which means a person who is sensitive to cold.) and highly chance of rain or cloudy days. The thing I am afraid of is “花粉症（かふんしょう・Kafun shô）” which is pollen allergy. If you do not have “花粉症（かふんしょう・Kafun shô）”, you do not need to worry about it.
Or in October and November are also beautiful. If you want to see 紅葉（こうよう・kôyô) which is changing color of leaves, November is the best.
Are you looking for activities in Japan?
You can book a lot of activities in Japan via link below! If you want to join local, this will be the best choice of your visit to Japan!
Here are a bit of examples. * Price may vary with the dates.
Japanese version Yelp, Tabelog
If you are looking for great or local restaurants in Japan, this website is a great choice! You can make a reservation as well.
I don’t recommend June and earlier July
Because it is a rainy season.
I don’t recommend August
Because it is extremely hot! You will melt. I am not kidding. Summer in Japan is humid and hot (as hell)… Sometimes it goes up until 40 ℃.
Once you are out of a building, you immediately sweat. You have to stay hydrated and eat salt!
I don’t recommend September
Because it is a typhoon season. Due to global warming, recent typhoon season comes to earlier than when I was little, though.
A Perspective of Holidays (crowd alert! )
Depending on where you visit, it changes. I cannot pick a specific BEST season regarding this, but I can tell you to be careful about Japanese long holidays.
I should have named the title of this paragraph to ‘I do not Recommend to Visit Japan During Those Period’.
1. – in January –
From January 1st to 3rd are called 三が日（さんがにち・sanga nichi). Most places, even shops, are closed. Hotels and コンビニ (Convenience stores) are open, but you have no place to visit during 3 days. Even though you have Japanese friends to visit, お正月（おしょうがつ・oshôgatsu) is a holiday for families. We visit relatives from the 1st to the 3rd of January. Therefore, it is hard to find someone hang out with. In my case, the 1st and the 2nd was my grandparents’ house on my mother’s side since we live close and we see my cousins, uncles and aunts, and the 3rd was my paternal uncle’s home.
2. – in March –
Elementary school and junior high school students in Japan have spring break around from March 23rd to the first Sunday in April.
That being said, because it is the spring break season, and (I am not sure about other countries, but let me write just in case) Japanese students cannot be absent easily from school for the reason of family trips, etc. Most of the families with children at that ages go on a trip during that period.
Hotels are expensive, it is hard to book Shinkansen if you do not make a reservation earlier, everywhere you visit is crowded, etc.
3. – in April and May –
Because Golden Week, which is the most exciting holiday in my opinion, happens.
From April 29th to May 5th are called Golden Week because several national holidays are in a row. The length is depending on the year and company, some people’s Golden Week can be longer and shorter, but in calendar, it is from April 29th to May 5th.
4. – in August –
Because お盆休み（おぼんやすみ・obon yasumi) happens.
お盆休み is not national holidays. From around August 11th to 15th, Most of Japanese company close their business. It is only for Japanese company which headquarters are located in Japan . When I was in Tokyo, I worked for a company based in Switzerland. We did not have お盆休み, sadly. This is also depending on which industry you work for. Like me, Shipping and trading related company do not have お盆休み because ships discharge in ports without stopping.
お盆休み is for Japanese company because it is related Buddhism. お盆休み is holidays for visiting our ancestors. In my case, my father is originally from northern part of Japan, and it took 10 hours to go from where I am originally from. Now, new high way opened, so we can get there about 8 hours. Every summer, we visited paternal grandmother and relatives. I could see them only 5 days per year. During our stay at grandma’s house, we visited tombs of our ancestors early in the morning, and at night while playing with fireworks, we make small fire so that our ancestors can visit us without getting lost.
Vegetable Horses : Speaking of お盆休み, people imagine those things on the picture below. This culture is not everywhere in Japan. Because I saw them only in my paternal grandmother’s places which is in the northern part of Japan. My hometown, which is Nagoya, does not have this culture.
A Perspective of the Budget
This is the same as above, A Perspective of Holidays (crowd alert! ). The more people are on vacation, the more prices get higher. That is how business works and it is logic. Japanese company are still not willing to give payed vacations to employees. Therefore, a lot of people go travel during those national holidays.
Bon Voyage to everyone!