I love me some old horror movies. Especially hidden gems. Back in the fifties there was a Japanese movie studio called Shintoho. It was known for trashier genre movies including horror. The most well know movie to come from Shintoho was Jigoku. Around 2001 a bunch of Shintoho movies came out on DVD in Greece that luckily came with english subtitles and weren't region encoded. I've managed to get all the horror ones and a couple others. Here's The Ghost Cat of Otama Pond (aka Kaibyo Otama Ga ike)
From watching a lot of old Japanese horror movies I've gathered that the vengeful cat ghost must be an old traditional Japanese ghost story. There are a lot of movies where a person dies a wrongful death and their cat happens to be around to drink their blood, and they then come back as a cat/human ghost to take vengeance. The vengeful cat ghost is almost a genre unto itself.