Sasasegawa Sasami

Sasami is a girl at Riki's school and is Rin's rival. Surprisingly, while Rin loves cats, Sasami is a devoted dog lover. Due to this, she will often get in a fight with Rin, though since she is the captain of the girls' softball team, she will send in three new team members first before she goes in herself. Sasami's name is thought to be a tongue twister, which even she manages to mix up.

Spoiler

The reason for her avoiding cats is due to the disappearance of her own cat Kuro during her childhood. In Sasami's route, which happens after the events in Refrain, Sasami's cat Kuro created a world similar to the Little Busters! world around the school, in order to meet Sasami one last time before dying.

From Wikipedia