"New Zealanders read a really wide range. They're willing to try authors from all over the world, and they're up for anything. Maybe it's because we're at the bottom of the world."
While the shelves are laden with books for every age and taste, she's noticed the natural history section is particularly popular at the moment.
"People are keen on books about wildlife, and stories where people and wildlife intersect."
Jo started the shop in 1989, and despite its tiny size, she loves the location and wouldn't consider moving. With more than 25 years of experience running the show, she's seen all manner of book trends come and go.
While some said e-readers would spell the end of bookstores, Jo reckons the book trade is stronger than ever.
"Kindle sales have leveled off," she says. "Anybody who was interested in them has tried it, and some liked it, others didn't. We've noticed an increase in sales, and most independent bookstores will say the same."
With most suppliers based in Australia, Jo and the team do the bulk of the book buying from a computer screen. While ordering, they usually have a fair inkling of what will sell well with Unity customers, and this is often confirmed once the books arrive at the shop.
"As well as the subject, it's the size of the book, the texture of it, the font inside - all of these things can make a bestseller."
A job in a bookshop was the first role she landed after leaving university, and Jo's been dedicated to the book trade ever since. And if having three other staff members who have each worked at Unity for more than 20 years proves anything, it's that bookselling can become more of a passion than a vocation.
For Jo, seeing the next generation enthused about reading is one of the best parts of the job. "The kids get really excited," she says. "It's gratifying to see kids' energy for books. We have uni students who hang out in the shop, and they're into philosophy or working their way through the classics. Really, it's like a big family."
Unitybooks.nz
See a different side to your city. There are 50 secrets waiting to be discovered at heartofthecity.co.nz/lovebites
Find more Lovebites of Auckland city here