Okay, so I read Pat Me Please (the novel) then a bit of Night Tide. The latter is a sequel in that the main characters from the former return and that a lot of the character building that the girl who time travelled received is covered in Pat Me Please.
I think it would not be impossible to guess at certain character beats, but Pat Me Please does build three characters that Night Tide does expect you to know. Also, Night Tide’s intro already spoils the ending to the love triangle (angle?) of Pat Me Please.
Pat Me Please might be required reading for this manga if you are already confused…