What is the ruling on watching Japanese anime that contains music and creedal violations, and what is the legal evidence for its prohibition for one who claims to watch it merely for entertainment and is not affected by it?

It is not permissible to watch films that contain unlawful acts and Sharia prohibitions, whether they are related to creed or practice, intellect or behavior, even if they do not change the viewer's creed or behavior. This is because what is inherently forbidden is forbidden to look at, as it constitutes an affirmation of the unlawful act.