The old lab in the mountain.

"Welcome to the CAT Research Facility, located at ⬛️⬛️⬛️⬛️⬛️⬛️, Japan. You may be wondering why we built our facility in the same place as AnimeRice⬛️⬛️⬛️⬛️? Why, because why not? It's here, so might as well help an old buddy out eh?"

"Something just.. feels.. off. You know what I mean, right? It's.. spooky."
"Oh not about that game again.."

4 kids find an abandoned installation of some sort in Japan. They all know that it was never there, so they check it out. What awaits them, you'll have to find out...