Think you're a Potterhead? Think again. Meet the most obsessed Harry Potter fan in the world.

·Senior Producer, Yahoo Entertainment

On Sept. 1, 1998 — 20 years ago this week — a phenomenon was born: Harry Potter and the Sorcerer’s Stone, the opening installment in what would become J.K. Rowling‘s epic saga, was published in the U.S.

In honor of the anniversary, Yahoo Entertainment set out to find the biggest, most committed, most obsessed Harry Potter super-duper fan in the known Muggle universe. The answer is right there in the video above. Her name is Katie Aiani.

Aiani’s Harry Potter obsession started when she was about 11, and from there, she eventually became a full-fledged Potterhead. She started going to midnight movie premieres and fan conventions all over the world, and her latest obsession is going to Harry Potter Wizarding World at Universal Studios Hollywood about three times a week.

But that’s not the only way she is wild about Harry. From collecting the first book in different languages…

Harry Potter books in different languages
Photo: Yahoo Entertainment

…to all the movie posters…

Aiani's movie poster collection.
Photo: Yahoo Entertainment

To toy figurines…

Aiani's figurine collection
Photo: Yahoo Entertainment

Aiani’s memorabilia collection comprises more than 3,000 items.

Aiani was so inspired, she eventually wrote a letter to Rowling sharing her unparalleled Potterphilia. Rowling then did the unthinkable — she wrote back. From there, Aiani did what the ultimate Harry Potter super-duper fan would do: She immortalized a message from Rowling’s missive in ink. Aiani’s one-of-a-kind tattoo reads: “Keep fighting. You’re inspirational. With love and admiration, Jo.”

Aiani's J.K. Rowling tattoo
Aiani’s J.K. Rowling tattoo. (Photo: Yahoo Entertainment)

Come back tomorrow for the next installment in our Harry Potter and the 20th Anniversary series.

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Watch: J.K. Rowling on what it was like seeing Harry Potter in a bookstore for the first time:

[Editor’s note: A version of this story and video originally was published in 2016.]