Punch, the orphaned monkey at a Japanese zoo who won hearts around the world by cuddling an orangutan plush toy, is celebrating his first birthday on Sunday with thousands of birthday messages from admirers.

Although Punch no longer carries the toy and now happily plays with other monkeys, he remains one of the biggest attractions at the Ichikawa City Zoological and Botanical Garden.

Punch was abandoned by his mother shortly after birth a year ago, likely because she was exhausted. Zoo keepers hand-raised him and gave him a stuffed orangutan to help him develop the gripping skills newborn macaques need to survive.

Now fully grown into an active young monkey, Punch blends in with about 50 other monkeys in the enclosure. Still, visitors continue to flock to see him.

According to zoo director Takashi Yasunaga, Punch has received around 2,500 birthday cards and messages from supporters in Japan and abroad. Many of them are displayed at a special birthday exhibition inside the zoo, where visitors can also watch videos showing Punch's journey from his first days.

Yasunaga said the past year had been unforgettable for the zoo staff, recalling how two keepers devoted themselves to caring for Punch during the hot summer when he was born.

After six months of special care, Punch joined the monkey enclosure in January. Adjusting to life with the other monkeys was not easy, but it was during this period that he became an internet sensation.

In February, photos of Punch hugging his plush toy after being pushed away by other monkeys went viral on social media, attracting tens of thousands of visitors to the zoo, about half of them from overseas.

Supporters rallied behind him using the hashtag #HangInTherePunch, inspired not only by his adorable appearance but also by his determination to earn acceptance from the other monkeys.

Among those visiting the birthday exhibition was Kumi Ishizawa from Kobe, who said she first discovered Punch on social media while recovering from an illness.

"He inspired me," she said. "I kept telling myself I would get better and come to see Punch. Now I've finally made it, and I'm so happy."

Another fan, Yeye Lights, who has lived in Ichikawa for years, said she had never visited the zoo until her daughter in the Philippines introduced her to Punch online.

She has since become a regular visitor and even bought an annual pass.

"I have a cake for Punch-kun and I'm celebrating with my friends," she said, while thanking the two keepers who raised the young monkey.