Prior to the introduction of new guidance, before including Japanese participants into a multi-regional clinical trial (MRCT), the sponsor needed to conduct a standalone Japanese phase I study to ensure no significant difference in safety/pharmacokinetics (PK) between Japanese and non-Japanese participants. This requirement has been considered an obstacle for non-Japanese companies to conduct MRCTs including Japanese participants, which can lead to drug lag* and drug loss* in Japan. Based on this, the Ministry of Health, Labour and Welfare (MHLW)† took this situation seriously and reviewed the requirement for standalone Japanese Phase I trials.