Visiting Japan from Taiwan?
 

Reading official Japanese government sites, it says
Until further notice, the GOJ will deny permission to enter Japan to those foreign nationals who have beenphysically present in the U.S. or other countries/regions listed in the below link in the 14 days prior to their arrivalto Japan, as they fall under Article 5, paragraph (1), item (xiv) of the Immigration Control and Refugee RecognitionAct, unless there are “Exceptional Circumstances.”→mofa.go.jp/ca/fna/page4e_001053.html#section1
la.us.emb-japan.go.jp/pdf/ImportantGuidanceOnJapansBorderControlMeasuresRela tedToCOVID19.pdf
Does this mean you can go to Japan if you’ve been in Taiwan for 14 days?
mofa.go.jp/j_info/visit/visa/short/novisa.html
Visa wise, it seems like if you're a US citizen, that link states that 68 countries' visa waiver programs are suspended, except for the shaded countries, which includes the US.

I could not open any of the links you gave.

I would not begin a trip based on info received here on Fodor's forums. You should contact a consulate or embassy to get a confirmation.