Tolong jelaskan mengenai Heart Sakebu dari Don't Look Back!

Tim M: Yuki Azuma, Akari Ishizuka, Ayaka Okita, Rena Kawakami, Momoka Kinoshita, Rina Kushiro, Rina Kondo, Miru Shiroma, Yui Takano, Sara Takei, Airi Tanigawa, Reina Fujie, Arisa Miura, Mao Mita, Ayaka Murakami, Sae Murase, Fuuko Yagura, Nana Yamada, Azusa Uemura, Megumi Matsumura, Reina Nakano, Ayaka Morita, Mizuki Uno