There's some stuff called "Mr. Color Thinner 50", by a company called MR Hobby --- and I can't tell you any more about it because it's a bottle with only Japanese for all the other text. A friend bought it (from Japan?) and gave it to me. But it takes the logos, lettering and paint off KATO stuff really fast, like about 2 minutes. I've only used it for car name removal and never a full car dunk so I don't know what happens then.
Someone told me that KATO uses soy-based paints, don't know if that's true. But it could explain why conventional methods have little effect on it.