Tumi

Tumi is a girl, who became friends with Lisa.

Background
Fearing that Lisa will grow up having no friends, Marge secretly paid Tumi to hangout with Lisa. As Tumi and Lisa hung out, Bart became suspicious of Lisa's new friend.

Bart began to investigate Tumi. Eventually, Bart discovered that Marge had been paying Tumi to be Lisa's friend. Bart would subsequently reveal the information to Lisa, much to her shock.

Afterward, Lisa told Tumi they had to be honest with each other in order to stay friends. When Tumi revealed that she's not an actual vegetarian, Lisa to ran off.

Personality
Tumi was nice to Lisa, despite being paid to hangout with her. She and Lisa bonded well throughout the episode. It was also revealed that Lisa only sees Tumi during tornado drills, due to the fact Tumi is in the other second grade class.