Protagonist Kusaka Minato lost parents when he was young and lived with his brother. Although there was some loneliness in his life, the house left by his parents and thanks to the elder brother there were no inconvenience. Time will flow before long, the elder brother becomes a member of society, the marriage partner is brought.

The partner Yukari in a bright, kind woman, a serious elder brother though it is a little unfriendly?, it was a very well matched couple seen from Minato. Minato and Yukari also become happily though a suitable distance is kept as younger brother and sister-in-law. The daily life of the Kusaka house that added Yukari was calmly.

[I'm frustrate] Until one problem is noticed. [Because the human nature and the penis is another problem] ... no, umm. [So why don't you give me some cooperation]

Yukari-neesan, isn't it somewhat different from usual?