One day during summer vacation, a customer orders an unadon (eel bowl) that is not on the menu, and Yoichi begins his challenge to make unadon. He visits the long-established Unagihama restaurant to obtain high-quality eels, but ends up in an argument with his stubborn father, Eikichi. With the consideration of Shiba Hiroyuki, who happens to be present, Yoichi agrees to share the eel if he can make an unadon that impresses Eikichi.
夏休みのある日、客からメニューにないうな丼を注文された陽一は、うな丼への挑戦を始める。良質のうなぎを手に入れるために老舗の「鰻浜」を訪ねるが、頑固親父の永吉と言い争いになってしまう。
