An elderly penguin who became a local celebrity in Japan after falling in love with a cardboard cutout of a cartoon character has passed away - with his paper partner by his side.

Grape-kun became enamored with the cutout of an anime character in a penguin dress after it was placed in his enclosure at Tobu Zoo, in Miyashiro, during an advertisement campaign in April.

Today, zoo staff reported that 20-year-old Grape had passed away after a short period of illness, but that the cardboard had been with him 'until the very end'.

After losing his partner of ten years, Grape-kun's luck changed after a cardboard cut-out of a character from the hit anime series Kemono Friends was installed in the penguin enclosure

The tale of the penguin who loved a cardboard cut-out saw Grape gain millions of fans all over the world as the story hit the news.

The unlikely romance began after Grape was 'dumped' by a female called Midori with whom he was coupled with for ten years.

Zoo staff were concerned for Grape after the end of his relationship with Midori, who left him for a younger penguin.

He began spending less time with other penguins, and more time wandering alone, according to staff.

However, his luck changed after a cardboard cut-out of a character from the hit anime series Kemono Friends was installed in the penguin enclosure.

Heartbreaking: When staff were forced to remove Hululu ahead of a typhoon, Grape-kun was pictured slumped in despair

Grape's true feelings were all but confirmed when he was observed standing before the cut-out with his wings outstretched and his beak pointed up - a penguin courtship ritual

The character, Hululu, is a petite girl wearing a short dress with a penguin-like pattern and headphones.

It was not long before zookeepers began noticing that Grape was spending more and more time staring at the cut-out, much to the amusement of zoo visitors.

Grape's true feelings were all but confirmed when he was observed standing before the cut-out with his wings outstretched and his beak pointed up.

The stance is a courtship ritual in the penguin world, and an indicator that Grape could be ready to take his relationship to the next level.

Until the end: Zoo staff said Grape-kun, who at 20 was considered an elderly penguin, had passed away on Thursday, with the cardboard cut-out by his side

Shortly afterwards, zoo staff were forced to remove Hululu during a typhoon - for fears she would blow away - and the penguin became so visibly heartbroken she was soon returned to him.

Earlier this week, the zoo posted on social media that Grape had fallen ill and would not be appearing in his enclosure.

On Friday, the staff tweeted: 'The Humboldt penguin Grape-kun passed away yesterday. Sincere thanks to everyone for supporting him until now.

'Thank you also to Hululu, who watched over him until the very end. And thank you, Grape-kun, for all this time. Rest peacefully in heaven.'

Grape-kun was a Humboldt penguin, and their average life-span in captivity is around 20 years.