Masao Gunji, who spent his working life on the trail of hardened criminals, now spends his retirement tracking down pink and white soft toys to keep in a Hello Kitty-themed house, which he built specially and has become a magnet for tourists.
"Kitty has been like the love of my life," he said at his one-story property, which is surrounded by regular houses.
"I love Kitty," he added, calling her "adorable, especially her facial expressions".
Hello Kitty, Japan's global icon of cute, was introduced in 1974 and is now one of the country's most famous exports -- adorning everything from pencil cases to pajamas.
To the surprise of fans, brand owner Sanrio said in 2014 the feline-inspired character was not actually a cat but a "happy little girl", sparking uproar from Internet users who spluttered: "But she's got whiskers!"
Though he doesn't live in the property, Gunji was recognized last November by Guinness World Records for his collection, having spent around 30 million yen ($267,000) on thousands of items, including the house.
More than 5,000 items he owns bear Kitty's iconic red bow, propelling Gunji past the previous record holder, also Japanese.
Gunji's wife Yoshiko says she fully supports her husband's passion.
"I don’t care how much he spends on Hello Kitty," she said.
"People need to make a mark on the world, and Hello Kitty is the one he lives for," she added.
"This is his dream."
© Agence France-Presse