The spam pattern becomes clearer if you look at the posting history for articles from this site: https://news.ycombinator.com/from?site=learnjapanese.best It's a pretty consistent pattern of once every couple of days.

If you look at the post history for the spammer's main account, they try to disguise their spamming by posting a few miscellaneous Wikipedia articles and the like between posting their site: https://news.ycombinator.com/submitted?id=sova

You can also see them experimenting with spamming their other sites as well; the poster is always the same individual.

https://news.ycombinator.com/from?site=japanesecomplete.com

https://news.ycombinator.com/from?site=learnjapanesebest.wor...