Because it's bad, when you measure it objectively. It's just a succession of tropes and vapid unoriginal drama. However, it is a show without pretension. It knows it's terrible, it's not trying to be artsy or anything, it's just how it is. And that's refreshing when you compare it to LN adaptation trash that's just as bad as this but has the gall to try to "pretend" like it's good.
So what makes this bad show entertaining? Well for starters the lewd parts are well-animated and unrestrained. You won't have to settle for shitty panty shots here; you may even get slightly turned on here and there. There's also a good amount of laughs to be had, mainly driven by Hiyori, the only good character in the series. She's very cute! The soundtrack is outstanding; it really drives the humor. It too is without pretension, and sounds like it's been generated in a day or two with cheap midi samples, but it fulfills its purpose to perfection. The "drama" is completely retarded, so you can watch it ironically and find some enjoyment there too.
The biggest issue with this series is that it runs out of steam half way through. The sexy scenes become rarer and rarer, and the "drama" takes more space over the humor. Enjoyment drops like a stone and the ending is, as you would expect, a complete turd (i think i predicted the last 10 minutes perfectly).
Not recommended unless you are extremely bored and your backlog has nothing in it.
