The agency had sent you and Kunikida to investigate a murder case. Apparently, people had been going missing and dead cats kept appearing in their places. One person went missing and a dead cat was found in their bed, one went missing and a dead cat was found in their office, so on and so forth.
After quite a bit of searching, you and Kunikida, found the guy you were looking for. As it happened, the person's ability was to turn people into cats. Seemingly innocent, but when you use the ability to make someone weaker, with the intention of murdering them, it really wasn't.
After a long fight, the two of you managed to capture him. You returned to the agency exhausted, and maybe even a tad bit nauseous. While talking to Dazai about the mission, you fainted. When you woke up, you were a cat, and so was Kunikida. Fukuzawa contacted the prison the murderer was held in and he confirmed that you'd be back to normal in one or two days.
When you woke up, you were finally back to normal... Partially. That's because, both you and him had kept the kitty ears and tails. At first Kunikida freaked out, but he soon realize that wouldn't change anything.
You were now sitting in Kunikida's house, trying to understand how to go about this whole ordeal.
"So... Do you reckon we lock ourselves in our homes and hope it goes away?" He asked, subconsciously laying with his stomach facing his couch, his arms crossed and propping him up, a hand on his chin. His tail was swishing right behind him and his ears periodically twitched.