Speaking of seasonal foods, one offering I like during Japanese hot weather is cold noodles. Japanese eat noodles as meals in Japan, but a huge bowl of hot noodles will cause you to sweat profusely.
Nice alternatives are cold noodle dishes such as reimen (冷麺), a cold ramen dish, or somen (素麺) which is made from different ingredients and is often served on ice. Reimen has a stronger taste, while somen depends just on the taste of the noodles and the diluted soy sauce based dip. Somen really cannot be beat and I know of Japanese who choose somen for their first meal back in Japan after a long overseas trip.