Nothing, as long as it doesn't exceed 30kg. It is best to indicate clothes in Japanese or English when mailing. It shouldn't matter if the standard is lowered. It's just that sometimes it's spot-checked If there are several identical clothes, you'd better send them separately.

In addition, Japanese writing can be written as "general paragraphs" (daily clothes) and "clothes" (clothes), and the amount should not be too high. Japan stipulates that the total amount should not exceed 200,000 yen (about 1.5 million RMB).