It seems to be "whenever the Hell the artist feels like it", since the last three have come out within a single week, but the one before that was a month ago.
Oi Tabuchi, don't just stand there!Steel pipeUgh
A-All right.GISSHAAAAAAAAAAHIt's working!Nasty...I don't like having to harm a creature this cute...It looks like it's made of cloth so it's burning great!Ah, Tabuchi-kun poured gasoline on the monster's face and set it on fire!I said that, but this monster still looks like a plush doll.