Apparently it started with this tweet showing official art of Michiru photoshopped with a crop of a man's hands kneading dough and Riamu's face photoshopped onto the dough ( https://twitter.com/Ginko_02/status/1235379661145649152 ), which was then interpreted via that cat image macro into Psychoorbevil's pair of images you linked, which in turn was recast with Mokou and Eirin here by jokanhiyou.
Apparently it started with this tweet showing official art of Michiru photoshopped with a crop of a man's hands kneading dough and Riamu's face photoshopped onto the dough ( https://twitter.com/Ginko_02/status/1235379661145649152 ), which was then interpreted via that cat image macro into Psychoorbevil's pair of images you linked, which in turn was recast with Mokou and Eirin here by jokanhiyou.