DNA paternity testing has recently become more widely available in Japan. The aim of this paper is to examine the issues surrounding the implementing agency, whether the testing is conducted in a commercial direct-to-consumer setting or a judicial non-DTC setting, and the implementation conditions and more specifically the legal capacity of the proband. Literature research in Japanese and English was conducted. Some countries prohibit commercial DNA testing without the consent of the proband or her or his legally authorized representative. But (...) as in some cases, the results of DTC paternity testing have proven to be unreliable. I propose a complete prohibition of DTC DNA paternity testing in Japan. In many cases of paternity testing, the proband is a minor. This has led to debate about whether proxy consent is sufficient for paternity testing or whether additional safeguards are required. In cases where commercial DNA testing has been conducted and the test results are produced in court as evidence, the court must judge whether or not to admit these results as evidence. Another important issue is whether or not paternity testing should be legally mandated in certain cases. If we come to the conclusion that DNA test results are the only way to conclusively establish a parent-child relationship, then our society may prioritize even more genetic relatedness over other conceptions of a parent-child relationship. This prioritization could adversely affect families created through assisted reproductive technology, especially in situations where children are not aware of their biological parentage. This paper argues for a complete prohibition of DTC DNA paternity testing in Japan, and highlights that broader ethical and legal deliberation on such genetic services is required. (shrink)