If life teaches us anything, it is that love sometimes happens in the most unlikely of places, with the most unlikely of people. Koshiro is a run-of-the-mill salaryman who has recently been dumped by his partner. With his heart broken and hope lost, he soon comes to realize that he can love again, once he sets eyes on a beautiful young schoolgirl riding the train. However, there is one catch -- this girl named Nanoka is his sister, who he has not seen in years. Knowing that their forbidden love will always be scrutinized by society; will Koushirou and Nanoka be able to resist the temptation?
Tatsuhiro Sato is a university dropout and a "hikikomori" – a person suffering from social withdrawal. To Sato’s dismay, his self-imposed exile from the world is rudely interrupted when a mysterious girl knocks on his door. She has charged herself with the task of curing Sato of his hikikimori ways! Now, as new problems ranging from hentai games to internet suicide spring up, can Sato manage to overcome his hermit-like ways, or will the imaginary N.H.K conspiracy force him to remain a hikikomori forever?
Though quite different plotwise, these two anime in my opinion give out the same atmosphere. Despite the fact that you will find none of NHK's comedy in Koi Kaze and there is no theme of forbidden love in NHK, both these shows deal with characters whose troubles are kinda out of the ordinary and they both get very dramatic at times.