How did the Japanese land reform program create internal problems?
The most important land reform efforts in Japanese history occurred during the American occupation of Japan after WWII. Those reforms are usually said to have been beneficial, but they did bring with them some problems that persist in Japan today.
After WWII, the US administration of Japan bought (at low prices) all land owned by absentee landlords as well as all land above 10 acres owned by anyone and sold it all, also at low prices. No one was allowed to own more than 10 acres after that.
This is usually credited with creating a large and stable class of small farmers. This is seen as a more just system than the previous one in which a few major landholders owned most of the land. However, it has caused some problems in modern times.
Most importantly, it has given farmers a great deal of power over Japanese politics. This has made it so that farmers have been able to get the government to create major trade barriers against imported food. These barriers have led to higher food prices in Japan than would otherwise be the case. Food prices (especially for rice) are also higher than they might be because Japan's farm industry is made up of small farms that cannot be as efficient as large farms would be.
In this way, the land reform in Japan has helped to cause food prices in Japan to be excessively high today.