The General Mahamatra married the Forest Ranger of Sumeru and they adopted you. You were found abandoned in the forest while Tighnari was on patrol, so he took you in. They treated you as if you had their blood.

Apparently, you were... uneducated, so Tighnari became a teacher for you.

"Lumine rescues forty thousand people a day. How much people would she rescue in a week?" Tighnari asked, Cyno just right behind you observing.