Spanning 25 years "Kimagure Concept" is the longest running 4koma Manga in Japan.

Taken from the book's jacket:

"A Capricious Concept" is a 4koma manga that has been appearing serially in Big Comic Spirits since October 1981. Every Japanese had turned their eyes towards "Industry", which stood for the Mass Media such as broadcasting, advertising, and publishing. And many college graduates aspired to join those firms. "A Capricious Concept" began as an unusual manga that revealed the hidden secrets of Industry.

Early works were compiled into a book in early summer 1984, but there has been no such opportunity for the next 23 years. In this book 23 years' worth of work has been reduced to 1/3 and arranged in cronological order, as a result the book became a time machine. People's everyday lives in pre-bubble, bubble, and post-bubble days, the recession in the 90's, the spread of cellular phones and the Internet, and the economic recovery of 2006 are all in this book.

Get on the time machine everyone, and enjoy your trip to the past. Go on to the days of the bubble!