The dog days are just beginning for this man.

According to the New York Post, a Japanese native has transformed himself into a canine after forking out more than US$14,000 for a custom-made collie costume.

The private citizen, who goes only by Toco online, says the unusual garment has helped actualise his dream of “becoming an animal.”

Footage shared to Toco’s YouTube channel, where he boasts more than 32,000 subscribers, shows him clad in the costume as he frolics on a lawn, rolls on a floor, and plays fetch.

Toco has even uploaded a video of himself venturing out in public as a dog for the very first time.

He completed the costume with a harness strapped around his furry abdomen, but admitted he was “nervous” and “scared” of venturing out in public.

“Do you remember your dreams from when you are little? You want to be a hero or a wizard,” he wrote in the clip, describing his life-dog dog dream as seemingly “unrealistic.”

“I remember writing in my grade school graduation book that I wanted to be a dog and walk outside.”

As an introduction to his unusual hobby, Toco answered a series of questions in a video posted last year, admitting he always “had a vague dream of becoming an animal” ever since he was a child.

“When I fulfilled that dream, this is how it turned out,” he wrote in the clip, adding that he chose to become a collie due to the negligible size difference between the breed and humans.

Meanwhile, the Japanese man said last year that most of his colleagues are also unaware that he dresses as a dog outside of work.

“I don’t want my hobbies to be known, especially by the people I work with,” he told the Daily Mail.