Summer in Japan is a popular time for tourists, but whether it's worth it depends on your interests and preferences. Here are some factors to consider:

Weather: Japan experiences a humid subtropical climate, and summer is the hottest and most humid season of the year. The average temperature ranges from 25 to 30 degrees Celsius (77 to 86 degrees Fahrenheit) in most parts of the country. However, some regions, such as Okinawa and Kyushu, can experience temperatures above 30 degrees Celsius (86 degrees Fahrenheit). Additionally, summer is also the rainy season in Japan, which can bring occasional typhoons. Despite this, Japan is well-equipped to handle the heat, with many indoor spaces, such as shopping malls and public transportation, being air-conditioned.

Festivals: As mentioned earlier, summer in Japan is the season of festivals, or "matsuri." These festivals are an important part of Japanese culture, and they take place throughout the country. They usually feature traditional music, dance performances, and food stalls. Some of the most popular festivals include the Gion Matsuri in Kyoto, the Nebuta Matsuri in Aomori, and the Tenjin Matsuri in Osaka. Attending a matsuri is a great way to experience the lively atmosphere of Japan during the summer months.

Scenery: Japan is known for its beautiful natural scenery, and summer is a great time to enjoy it. For example, the lavender fields in Hokkaido are in full bloom in July and August, and the sunflowers in Hokuryu are a sight to behold. Additionally, many of Japan's national parks, such as Hakone and Nikko, are lush and green during the summer months, making them perfect for hiking and outdoor activities.

Crowds: Summer is peak tourist season in Japan, and many popular destinations can be crowded. This includes trains, which can be very busy during peak travel times. However, with the JR Pass, you can reserve seats on many trains, which can be a great way to secure your spot and avoid the crowds. However, there are ways to avoid the crowds. For example, visiting popular attractions early in the morning or late in the evening can help you avoid the busiest times. Additionally, visiting lesser-known destinations can be a great way to escape the crowds and experience a more authentic side of Japan.

Overall, whether or not it's worth visiting Japan in the summer depends on your interests and preferences. If you're interested in festivals, natural scenery, and don't mind the heat and crowds, then summer can be a great time to visit. However, if you're looking for cooler temperatures or want to avoid crowds, you may want to consider visiting in another season.