Tolong jelaskan mengenai "Itoshiki Rival" dari Labrador Retriever (lagu)

Team K: Moe Aigasa, Maria Abe, Haruka Ishida, Misaki Iwasa, Mayumi Uchida, Rie Kitahara, Mako Kojima, Haruka Kodama, Kana Kobayashi, Moe Gotou, Haruka Shimada, Hinana Shimoguchi, Shihori Suzuki, Mariya Suzuki, Yuka Tano, Mariya Nagao, Jurina Matsui, Miho Miyazaki, Sayaka Yamamoto, Ami Yumoto, Yui Yokoyama