On a Silver Night, the Heart Does not Sway on the Water's Surface... (1)

Hei, Yin, and Mao are targeted by a group of contractors and now must fight to survive. Things become problematic when Yin goes missing. Now Hei and Moa must find her before the enemy does, but things change when Yin's old piano teacher gets Gai and Kiko to find Yin for him. The race is on to find Yin, but who will get to her first?