With a title like "Night Owl" and being tagged with "Monster Girl" I expected her to transform into a huge bloody Great Horned Owl mid-coitus and rip his head off with her beak.
Now this might be a casual fling between work colleagues, but the fact there's feelings involved and they want to date at the end I think qualifies it as vanilla.
Check the last page.
"Next issue: Exciting voyeur sex
Pure love is unleashed in the October issue!"
But to answer your question, I don't actually know. I presume it is weekly or monthly if it's a series of hentai stories. But at this point in time the author hasn't finished the next batch of stories, hence the deadline of October.
Probably one of those occasions where you think about something then blurt it out without actually meaning to. She was thinking about him having sex with other girls, so blurted it out.
How to get a girlfriend: >Hypnotise her and bring forth her closet pervertedness >Make her a slave to your dick >She will develop feelings for you through sex