Japanese future tense is same as Japanese present tense. See the example below:
I go to Japan. → 私は日本に行きます。
I will go to Japan. → 私は日本に行きます。
There are actually suffixes and sentence patterns which you could use to indicate future tense in Japanese, although you don’t have to use them as the present tense suffix（ます）is enough to show future tense most of the time.
Example of future tense suffix
I will go to Japan. → 私は日本に行くだろう。