Original Japanese Web Novel

Kazura buy lottery on a whim but he was selected as the winner and received 4 billion yen (about 40 Million US$).
To evade the hyena that smells the scent of money, Kazura take shelter on an old residence that was handed down from generation to generation.
When Kazura is investigating the place that would become his shelter, he stumbled on a certain room where it possible to come and go back into another world.
The Culture and Technology level of that world is relatively low. The protagonist sometimes brings goods, sometimes bring technological knowledge. At that world, he will find his value as a person.