I would personally highly recommend @
theg*ddam*hoi2fan's "
As One Star Sets, Another Rises": A TL in which the country of Japan from the year 2015 in OTL gets ISOT back to the year 1939, two years before the attack on Pearl Harbor.
In addition to the downtimes of 1939 from the rest of the world reacting to a militaristic and expansionist imperialist power suddenly replaced by a pacifist conservative democracy, since OTL Japan have lost territories such as the Southern half of Sakhalin Island afterWW2, you have the Japanese citizens from 1939 reacting to the rest of their country suddenly being 70 years more advance as well. Not to mention all the downtime Japanese soldiers fighting in China with their radically (To put things lightly) different social views having to find ways of integrating into a Japan that might as well be from another planet compared to the homeland that they have left behind.
Also, with the large number of American expats, tourists, diplomats, and most importantly, military personnel stationed in Japan, the same TL also explores the interactions between the uptime and downtime Americans, and the resulting cultural clashes on both sides as well.
I cannot emphasize just how much I recommend this TL, as it was one of the main reasons that made me become an active participant on this forum. With the TL inspiring so much discussion from the rest of the forum that it required
two threads in addition to the story only thread due to all the user discussions and ideas that it generated.... Discussions that are still actively on-going despite the last story post being made back in 2018.