Hi, Dominik. I've never watched this cartoon but I checked up on Internet and I'm sure IT'S CHINESE. These four words are "降世神通" (jiang4 shi4 shen2 tong1) in simplified Chinese. "降世" means gods or superpowered guys who belong to outer world come to earth. For example, Superman is from Krypton. We can call his coming to earth "降世". "神通“ means someone with super power or gifts, just like superman. So, "降世神通" means someone with superpower came to earth.