Rising US yields are attracting those investors who borrow Japanese Yen at the much lower rate and and then purchase American dollars to earn a higher return than in Japan - knowns as the carry trade. The correlation shows times when USDJPY carry trade is a key driver of the currency pair, however it is not always, because these are both go to currencies in times of fear, that's when the correlation between the yield differential breaks down. (E.g. in 2018 during the CHina US Trade War) However, since early Feb when the yields started to rise rapidly, investors have jumped in, selling Yen and buying USD. So long as rates continue to rise (and Powell gave no indication of YCC last night during his speech), this trend will continue. It's worth commenting that Japanese 10 Year Rates are also rising, however in absolute basis points, the rise in the US yield has been much higher. This carry trade will increase demand for USD and lend strength to the bulls case for a stronger USD in 2021.