Conan, Ayumi, Mitsuhiko and Haibara see Genta running with rice cakes in his arms. The owner of the eel restaurant "Ginpachi" injured his leg, so Genta was delivering unaju in his place when he found a group of curious onlookers gathering and was informed that the owner had been stabbed in the left chest and had collapsed. The Detective Boys decide to interview the suspects in order to solve the case, but... Genta's eel detective story begins in order to protect the peace of unaju!