For the uninitiated, Nande Koko ni Sensei ga!?, or Why are you here Sensei!?, is a romcom ecchi manga title. It's actually quite good, and I enjoy reading it myself. I was honestly surprised that an adaptation was announced, and that it's due to air in April. You'll see why in a bit, but first, a brief synopsis:

A sexy strict sensei shows her clumsiness to only one male student. 17-year-old Ichirou Satou is an average teenager who always happens to find himself in perverted situations with his teacher, Kana Kojima. Follow this erotic love comedy about their mishaps throughout their daily lives and how Ichirou and Kana choose to handle them.

Now, please take a look at the two trailers released so far. 

Now for why I'm surprised it's getting an anime series. There are parts that are straight-up hentai. Not just panty shots, straight up sex scenes you'd see in our galleries on Doujins. Take a look and tell me otherwise:

I had to take a second look, see if the anime adaptation wasn't just hentai. It's not. Regardless, this is a happy surprise. We can take a look at how far the mangaka Soborou is able to push the anime guidelines in April.