Tsukiko Masaki

Mother of Kiriko and Kai, Tsukiko was born and raised in Masaki Village, among the other descendants of Yosho and his first wife, Kasumi. She seems to be among the youngest generation, when seated for the pre-party before Rea's wedding, she was seated according to order of "joining the assembly," at the farthest end.

(Source: Tenchi Muyo Wiki)