Ichiro buys a lottery ticket on a whim and wins a staggering 4 billion yen.

To escape the hyenas who caught wind of his fortune, Ichiro takes refuge in an old mansion passed down through his family for generations.

While exploring the mansion where he sought refuge, Ichiro discovers that a certain room is a gateway to another world.

Into this other world, which appears to have a very low cultural and technological level, the protagonist at times introduces goods and at other times technology, striving to find his own worth in that world.

Main story completed.

Epilogues are being posted irregularly.

* Published as a book series under Futabasha's new label, Monster Bunko.

The book version is also complete.

All 18 volumes of the paperback edition are now available.

A comic adaptation is currently serialized on ComicWalker.

The spin-off manga "Marie's Isteria Commercial Development Log" is available in all 6 volumes on Gaugau Monster.