Nande Koko ni Sensei ga!?

Everyone loves their sensei 

Both animes with sexual themes and student/teacher relationships 

Series of relationships, include episodes for specific characters, short episodes, and has comedy in both animes but "Nande Koko ni Sensei ga!" has multiple ecchi scenes which can be considered as borderline hentai 

It's similar in episode Duration. But aside from that. It has a different plot where the funny and romantic relation between a teacher and student. Also the plot is very funny (If you don't mind the Ecchi-ness). Hence I recommend this one.  

If this is one step above hentai, B-Gata H-Kei is two steps. You like hentai? Good. You'll like this. 

a similar female big-tits teacher-male student situation. a main difference (personality-wise) is that Ayana from asamade was one huge airhead while kojima seems to be more down to earth.  

The same short anime that lasted 12 mins per episode, where it involves adult teacher and minor student romance, the differences, in one anime it was a hot teacher to a 17 year old male student while in Nobunaga it was more like an adult male teacher in a loli romance with a 14 year old girl.