Piece of Cake Two professional assassins, immature Kazuki and stoic Rei, assassinate a smuggler but are abruptly called away to care for their daughter Miri. Several months previously on Christmas Eve Kazuki and Rei share an apartment while operating as assassins with support from their handler Kyutaro. Kazuki is haunted by memories of his pregnant wife and is seen regularly sending portions of his wages to someone. Their next target is a human trafficker hosting a party at a hotel. Kazuki infiltrates the party delivering a cake with Rei inside the food trolley...