Sino ʻi ʻeiki/en

Mei he Wikipedia

When, in traditional Tongan society, someone has noble blood, because he was born, for example from a Tuʻi Tonga Fefine or Tamahā, it is said that he is noble by the body (sino ʻi ʻeiki). Such a person may not even want to be installed with a chiefly title, or may want to give it to a younger sibling. Or if he already is, not wanting to take the name of the title as his own, as such titles are lower. In addition, although they carry worldly power, they also carry worldly obligations.

As this type of titles is fixed to his or her blood, it remains forever. These titles are inherited through the mother: the blood flows forth from the woman, and child standing on/in the mother.

Compare with ʻEiki fakanofo/en. FOKI