@Ibri the manga had Halloween chapters but with the time table they had the halloween chapters were not going to be on halloween. So when halloween came around they went ahead and released the halloween chapters on halloween. At least that's my guess.
@phage83 I was replying to "what does that 'END' means?
end of volume one? it's end of volume 1, right?" I was implying that it can't be the end end because we already know chapters after this exist.