what are the expected effects of BOJ intervention to stabilize 30-year bond and yen

Hi,
After the recent run on Japan 30yr bond, there's some news that Bank of Japan may step in to stabilize yen.
I am trying to understand what are the possible impacts of BOJ stepping in to support ? Looking especially for possible impact scenarios in US market ( both fixed and equity).

Please explain like to a novice.

Thanks ( and much appreciate any response)