If someone is having a habit of reading the japanese news from NHK every day, here is a script that I modified to download todays news from NHK Easy in a single clean HTML and than convert it to MOBI format for your Kindle.

Here are the scripts, download the files in a folder and start it with bash file kindle.sh. You will need to have in the same folder Kindlegen (https://www.amazon.com/gp/feature.html?docId=1000765211) and also Python3 installed. (If you are in Windows OS probably you will have to run manually the python file and then kindlegen with the created .opf file.)

The MOBI file will have:
-all 5 news for today in one file
-vertical text
-right to left page flipping
-furigana
-correct word recognising for the Kindle japanese dictionaries (if you have paperwhite)