CRISPR/Cas9, a genome-editing technology that can efficiently modify genes, is also technically capable of "treating" genes for genetic diseases in human embryos. It could be a radical treatment for heritable disease. In addition, it could eliminate disease genes from the family. On the other hand, it is also possible to create "designer babies" which have the characteristics parents want. The use of the technology in human embryos has become a topic of international debate. The US National Academy of Sciences has been taking initiative to organize an international meeting among scientists, ethicists and patient groups around the world. In 2015, the first meeting issued a statement calling for a moratorium on the use of the technology in human embryos to obtain children. Now, an international committee, also led by the National Academy of Sciences, is debating what would be needed when the moratorium is lifted. In Japan, a law prohibiting the implantation of genetically modified embryos into a woman's womb is being drafted. However, Japanese governmental expert panel will follow the international trends to lift it in the future. How far should human permanent genetic modification be allowed? I would like to visit the United States, which is leading an international discussion on this issue, and interview some of the key members of international conferences, patient groups, ethicists, and basic technology researchers. Then I will write articles that will help us decide when to discuss the lifting of the ban in Japan.