GVH-609 Lauren Karen is an American lady who wants to marry Shunsuke, so she is introduced to his father, Yamada. Yamada, an old man, is outraged that his son chose an American woman instead of a Japanese one. He intends to test her by pretending to have a senile condition as a pretext.
Karen is eager to learn about Japanese culture and earn his favor, so she puts up with everything and begins to take care of him.
Bad Grandpa, however, takes advantage of the situation, leading to a variety of outrageous incidents, culminating in a creampie.
