Chiba's Myofukuji Temple is often referred to as the wisteria temple courtesy of a 750 year old wisteria tree on the grounds, and in typical years a festival is held while the flowers are blooming. Even though the festival isn't on the cards for 2021, the floral beauty can still be enjoyed.
Usually the best time to see the wisteria at their best is from mid April through to early May. Like any flower event, this can be subject to fluctuation depending on blooming conditions, so be sure to check the official temple website before you stop by. They post regular updates about how the wisteria are looking so that visitors can best plan their trip.