Japan in the year 20XX AD, Establishing the "Love Communication Studies" (commonly known as "lovecomyugaku"), a subject for studying romance, as an essential course for each school and the popular name "lovecomyu" was established.

At that time, the main character Hiroya Funaki who had been living abroad for a long time returned to his birthplace in Japan after a long time. He decided to live together in Japan with his sister's family, a childhood friend in my neighborhood who he played with when he was young. They became teachers and students in the school, and they have growing up beautifully.

By the way, Hiroya has spent his time so far in a research center for cutting-edge science and technology in Silicon Valley USA. Therefore, Hiroya who had been dealing with ultra-sensitive items and ultra-high-tech devices before they were out in the world, so he grew up to be a digital boy who is not good at socializing.

Therefore, even though he is a boy of about age, he has no interest in the opposite sex. So his sisters are worried.

"The way things are going, Hiroya will spent his life enclosed by machines and dies solitarily...! If it is so, we have to tell correct love."

In this way, days of "Sister Lessons" began.