Complex sentence: Coming from 2031,22 years in the future (arriving on Megumi and Nato's wedding date in the final episode), he comes back in time to ask his father's help to fight the menace that are making their way into the present.
Split into simpler sentences: Coming from 2031,22 years in the future arriving on Megumi and Nato's wedding date in the final episode. He comes back in time to ask his father's help to fight the menace that are making their way into the present.