How to Become Lovers with Your Best Friend

A male high school student named Katsuki has a beautiful girl who is his long-time best friend, Mayumi. The two of them are bound by strong trust and friendship, without fooling around or flirting with each other. The relationship between these two begins to change when a certain incident occurs in Katsuki's life. "I got love at first sight." "...Huh?" This is simply the story of two very close friends becoming lovers instead of best friends—a dialogue-based narrative up until that point. "...What kind of relationship are we?"