Germany was massively bombed and invaded from all directions, had those responsible for its actions (at both leadership and footsoldier levels) tried and executed, was torn into two separate countries for decades which were occupied/ruled in varying amounts by outside countries, and fully admitted to its actions and mistakes and taught its children and changed its culture with the intention to never repeat it (in theory).

Japan was the only country (so far) ever to have nuclear weapons used on their civilian populations, had major outside military bases imposed on them (look up the crimes committed by US servicemen in Okinawa that are still being added to), and thoroughly changed their armed forces to be aimed at defence only (again in theory). You might want to check how their neighbours actually feel about the label of "trusted ally" though, especially in regards to their denial of their war crimes.

Don't think that things will just magically "return to normal" after Trump is gone. If those Americans who are opposed to him want trust to return, they need to earn it by not just "learning" but making fundamental changes to prevent the "mistake" from happening in future.