Downloading logs from mjsoul is more difficult than from tenhou because it requires a login and the log formats are different.
For a long time, the reviewer had been able to retrieve mjsoul logs via tensoul, a tool I wrote to automate the process of login to mjsoul with an account, download of the logs and conversions to tenhou format. I created a dummy account and deployed a tensoul on heroku to provide a more accessible service, then the reviewer could retrieve logs in tenhou format directly by accessing the tensoul instance’s API. This was once hard coded in akochan-reviewer.
However, the heroku instance where tensoul is deployed (https://tensoul.herokuapp.com) seems to be banned by mjsoul recently as the login command keeps getting error code 151. Migrating the instance to another region could mitigate the problem, but I have already done it once. Currently both of the two regions heroku provides are banned and I have no choice.
Add this script to tampermonkey.
Login to mjsoul, open the log you want to review, then press S after the log is loaded.
Heads here (NSFW) and search for "Save logs".