extreme modification; crazy customization
Slang term for over-the-top, obsessive, or wildly creative modifications, especially of cars, plastic models, figurines, or electronics. Often carries a humorous or admiring tone.
His figurine has been so extremely modified that you can't tell what it originally looked like.
That car has been modified so crazily that it apparently can't be driven on public roads.
Compound of 魔 (ma, 'demon', 'magic') + 改造 (kaizō, 'modification'). The prefix 魔 intensifies the modification as something extreme, obsessive, or almost supernatural. The exact origin is uncertain, but it likely emerged in otaku and car enthusiast subcultures.