The latest instalment of Alice Oseman’s LGBTQ+ young adult Heartstopper series has become the UK’s fastest-selling graphic novel ever.

Heartstopper Volume 5 sold 60,012 copies in the first three days since its release on 7 December. This made it the overall best-selling book of the week in the UK across all categories including adult and children’s fiction and non-fiction.

The Heartstopper series follows the love story of two fictional British schoolboys, Nick Nelson and Charlie Spring, and explores friendship, coming out and mental health.

“I am completely blown away by the news,” said Oseman. “Heartstopper is a story I care so much about and for it to break records is something I could never even have imagined.

“Heartstopper is a story that centres joy, love and queerness, and to see it embraced in this way by so many readers, young and old, gives me a real sense of hope,” she added. “I am extremely grateful to all the fans who have supported me and the Heartstopper journey, it all feels incredibly special.”

Oseman’s latest book sold around 15,000 more copies than the second-placed book in the charts, Pinch of Nom: Express. The Heartstopper title also became the highest-selling children’s book in over two years.

The previous launch-week record across adult and children’s graphic novels was held by Joe Sugg, Amrit Birdi and Matt Whyman for Username: Evie, which sold nearly 14,000 copies in its first week on sale in September 2015, according to trade magazine the Bookseller.

The Heartstopper novels have been adapted into a Netflix series written by Oseman, the first two seasons of which have been released. A third season is currently in production. The first season won five Emmys in the inaugural children’s and family awards.

Oseman’s success is “well-deserved”, said Bea Carvalho, head of books at Waterstones. The author’s “portrayal of friendship and young love is wholly positive, relatable, and never patronising, garnering an incredibly loyal fanbase amongst teens and older readers alike.

“It has been great to see the sales of the books spike as a result of the successful and faithful TV adaptation: following the first week of broadcast sales rose by over 220% across the whole series”, she added.

Oseman is the third best-selling graphic novelist since Nielsen records began in January 1998, having sold £11.5m worth of copies. This comes in behind Alan Moore, the creator of Watchmen and V for Vendetta, at £13.1m, and Robert Kirkman, creator of the The Walking Dead, at £15.2m.

The initial four volumes of the Heartstopper series hold the first four positions in the all-time sales chart for adult and children’s graphic novels. 1.1m copies of the five volumes have been sold in the UK since their release.

Philip Stone, who works for Nielsen BookData, the company that publishes the UK book chart, said that “sales of graphic novels have boomed in recent years, helped by the popularity of adaptations on both the big and small screens. None more so than Heartstopper, the adaptation of which has become a global hit, earning rave reviews from critics and audiences alike, and propelling a boost in sales for its source material.”

The Heartstopper series was initially written as a web comic, published to Tumblr and Tapas. Oseman had begun the series during the final year of her English degree — a project that felt like “a very weird hobby” at the time, she told the Guardian last year. Oseman crowdfunded an initial limited print-run edition, meeting her fundraising goal in less than two hours, and Hachette Children’s Group published the first volume in 2019.

“We could not be prouder to publish the Heartstopper series,” said Hilary Murray Hill, chief executive of Hachette Children’s Group, who called Oseman a “once-in-a-generation” writer and illustrator.

“It has been a delight to see the graphic novels break new ground and change the publishing landscape. Reaching this milestone is a real testament to Alice’s incredible talent,” she added. “We recognise how important it is for teenagers to see themselves and their lives reflected in the stories they read.”

In April, Oseman announced that there will be a sixth part of the Heartstopper series, which she said would be the final volume.

“Heartstopper is now a truly global phenomenon, selling over eight million copies to date in 37 languages and counting, and the series continues to be embraced by readers everywhere – and of all ages,” added Hill. “Heartstopper is published for teenagers but seems to have a huge appeal for older readers too. It’s for everyone.”