So first it was Training with Hinako (I'll be using the translated names here,) in which a problem (lack of otaku exercise) was identified and a solution created (OVA attempting to get otaku to exercise.) Unfortunately this backfire: viewers get extra exercise, but only to the hands rather than the full gamut shown by the OVA.
Now we have Sleeping with Hinako (suggestive title, eh?) identifying this time lack of sleep among otaku as a problem, and resulting in a similar solution, this time as a sleep aid. Backfires because it's impossible to sleep with the fan service this OVA contains (I actually tried this, just to be sure. I ended up not getting any sleep at all and I'll be availing myself of the coffee soon.)
Next we'll have Job Hunting with Hinako. Playing into the plot from Training, Hinako is now out of a job (she failed to lose enough weight and her show got cancelled) and the OVA walks through looking for a job. This attempt at bettering the otaku market has no effect.
Playing off some scenes in Sleeping, there will eventually be Dating with Hinako, which attempts to get otaku to find a real person to love. This will backfire because the writers have Hinako fall for the viewer, leading more viewers to just date the TV screen rather than getting them out of the house.
By this point the writers will catch on to the fact that this just isn't working, but the franchise is so popular there's no point in stopping now. Rather than try to fix this, they decide to cash in. That's right, they'll release Sex with Hinako, heavily researched and expertly presented, 50 minutes of sex in various positions; A modern-day animated Kama Sutra. The market ends up being wider than just otaku, as normal people also get it to spice up their existing sex lives.
Now rolling in money the writers play along. For giggles, and to try and present a public-service facade, they turn "Training" into an OVA series with yearly releases, each with three new easy to perform exercises.
They also continue the established path of the previous installments, releasing in short order Married Life with Hinako and Parenting with Hinako (a three parter in itself.)
In the end, the writers realize that all things must end. After years of unremarkable releases that merely put off the inevitable, Retirement with Hinako is released, followed half a year later by feature-length animated movie narrated by Hinako, "Life with Hinako," and fleshing out Hinako's life and culminating with her death.
The movie is a huge departure from the established genre of the previous works, but the draw of getting a full view into Hinako's life after so many glimpses is huge. The story it tells is poignant and the movie is a box office hit. With some sadness the writers retire the franchise. There's simply nothing left.
They don't stop the sales though. The "with Hinako" series stays in publication for a little under a decade after the movie is released for purchase.