Yeah, it's an Olympic level stretch to call this "complete" when it didn't really have any over arching plot (the "climax" was in the first few chapters after she jumped his bones and they fucked, everything after that was essentially slice of life filler). There wasn't anything to conclude and they could easily arbitrarily add another "chapter" down the line if they feel like it as Kaos mentioned.
This is pretty standard for Zurikishi so it isn't a surprise but it does feel weird calling it the "End" when it "ended" about the same way plenty of their other series "ended", aka Zurikishi got bored of the character for now and decided to start drawing a new series.