Wow, that story was so much more depressing than the title let on. I was hoping for some sort of work on allocating resources for contact tracing or something.
Living in Japan right now...it's sure been a very bizarre time watching cases in Tokyo go from ~ 1000 in Tokyo down to 300 in about a week with no apparent explanation!
> 2021-06-07 B.1.617系統の変異株（デルタ株等） n=87 (+34)
> 2021-05-31 B.1.617系統の変異株（デルタ株等） n=53 (+24)
> 2021-05-24 B.1.617 インドで最初に検出された変異株 n=29 (+21)
https://www.mhlw.go.jp/stf/seisakunitsuite/newpage_00054.htm...
From the latest PDF linked there.
Hiroshima prefecture has gone from 1 case to 7 cases in 1 week.
Kanagawa prefecture has gone from 3 cases to 8 cases in 1 week.
We can suspect from experience in other countries (India, Malaysia, the UK, Vietnam, Taiwan, ...) that delta will out-compete other variants.
So if we wish to guess what COVID-19 cases in Japan will look like 3 months out (post-Olympics) it's best to focus on the rise in the delta variant.