Natsuo Fujii is a high school student who has developed strong feelings for Hina, one of his teachers; he knows any relationship is impossible so agrees to go to a mixer with friends. Here he meets Rui, a girl who surprises him with an unexpected request... she wants him to have sex with her so she can find out what it is like; she is not after a relationship. He accepts and afterwards doesn't expect to see her again. Shortly afterwards his father remarries and as well as a new step mother he acquires two step-sisters... Hina and Rui! His life is about to get complicated. In the background to this Natsuo has joined the school literature club as he hopes to become a writer on day.
I was a little unsure about watching this series but I'm glad I did. Thankfully it avoided gratuitous fan service and forced comic situations in favour a rather touching drama. It handles two taboos; relationships between step-siblings and those between a teacher and her pupil in a mature manner. This gives many genuinely emotional scenes as well as keeping the viewer guessing as to how his relationships will develop. There aren't too many main characters; this means that the characters of Natsuo, Hina and Rui can be developed impressively. The secondary characters are still fun and each contribute nicely to the story. The series has a solid ending which doesn't eliminate the possibility of a second season... I have no idea if there will be more but I certainly hope there is. Overall I'd definitely recommend this to anime fans looking for a maturely handled romance.
These comments are based on watching the series in Japanese with English subtitles.