Swallowed by a Beautiful Girl, Then I Encountered the Supernatural

One night, while I was walking by the lake, a beautiful girl turned into a goldfish and swallowed me whole?

Why have I met nothing but girls who can hardly be called normal ever since?

What is it that they have...?

To find the answer, and to pay off the debt I owe the girl who swallowed me because of her appetite, I have no choice but to set out on a journey.