Anime is an art medium, with no inherent moral properties. It cannot be either good or evil. The individual works must each be judged of their own accord.
There are several factors to consider when it comes to anime:
- It is a created by a culture that is largely Shinto, somewhat Buddhist, and very minimally Christian (and mostly Catholic of that). Most Japanese consider our religion to be a curiosity, at best. It is often used to give a show a Western flair, much in the same way they idealize the display of Victorian-era English elements in many shows. As such, there are often gross misrepresentations (even if unintentional) that display the Church in a bizarre or even negative light.
- It has very little concept of Western ideas of morality. Culturally, they view nudity, sex, religion, and occult differently than Westerners. A demon in an anime is not meant to be the same kind of demon as the Christian understands it. Christmas is not the birth of Christ to them, it is a couple’s holiday, much akin to Valentine’s Day. It is not unusual to find high schoolers sexualized in some way (even in shows not labeled for 18+ viewers). Catholic sensibilities will often find trouble encountering and reconciling these elements.
- There are often times very adult themes tackled in anime. Off the top of my head, shows like Neon Genesis Evangelion, Full Metal Alchemist, and Now and Then, Here and There all tackle serious questions relating to personal responsibility, death, morality, and many other difficult questions. The animated nature of the genre lends itself to younger viewership in Western cultures, but often times these younger viewers are not prepared to deal with the questions brought up in shows like this.
I’m sure others will chime in with more considerations. It is best to check into the rating on an anime before you dive into it, and when you first watch a show, explore it with a critical mind and eye. If you encounter elements that trouble you or don’t hold up to moral scrutiny, it’s okay to stop watching. Nobody is going to take away your otaku card

.
That said, if you don’t run into anything that is morally troubling, enjoy. People that want to marginalize as evil an entire medium of art are woefully out of touch.