The Bureau of Tokyo 2020 Olympic and Paralympic Games has published basic outlines of the basic designs of 4 Tokyo2020 Olympic venues. It concerns the Oi Hockey Stadium, Ariake Tennis Park, the Canoe slalom venue and the Dream Island Archery Field. The outlines were handed out for an Advisor Board meeting held at the end of June, where the progress of the basic designs were discussed.
The plans (in Japanese) are available here:
Source: Bureau of Tokyo 2020 Olympic and Paralympic Games Preparation