Contrary to popular belief, anime is not just for kids. In fact, there are a lot of mature themes in anime you need to be an adult to understand. So, how did we end up with the idea that anime isn't for adults? Maybe it's because in the Western world, animation is almost always aimed at children.
For some, the link between animation and kids' media is so powerful that a lot of American kids grew up watching totally inappropriate shows like Family Guy, Ren & Stimpy, or South Park. Their parents assumed that if it was animated, it must be kid-friendly. It could also be because the anime that gets imported over to the West tends to be aimed at kids. Anime-loving millennials grew up on Pokémon, Digimon, Sailor Moon, and DBZ. These series were also heavily censored in the dubbing process, making these already kid-oriented anime seem even more childish.
Animation in Japan isn't all Digimon and DBZ. There's plenty of anime for grown-ups out there. From sexual anime to series that feature drug abuse, some anime ask serious moral questions. In fact, a lot of what's on offer simply isn't appropriate for kids. So, if you're post-college and you're still into anime, don't worry. It's totally appropriate, and there are plenty of reasons anime is not just for kids.
While shows aimed at kids might make the occasional thinly veiled sex joke, they typically don't go beyond acknowledging that sex exists. They certainly don't show the act in question. While there's plenty of adult-oriented anime that can be viewed in polite company, some of it is better suited to... private viewing.
Some sexually explicit anime is ridiculous. For example, it's supposed to be super hot when some dude brushes his younger sister's teeth in Nisemonogatari. Some scenes depict the beautiful coming together of two people who love each other, though to be fair those scenes often fade-to-black. Some sex scenes are depressing. For that particular poison, check out the heart-stoppingly miserable sex that characterizes Scum's Wish. Some is disturbing, which you'll have noticed if you ever watched Berserk. Some is just straight-up erotic, and that happens more often than not. Obviously, none of it is even remotely child-appropriate.
There's no way to discuss complex moral decisions in anime without mentioning Death Note, so let's start there. For the uninitiated, Death Note focuses on Light Yagami, who finds a magical notebook that kills anyone whose name is written inside. He decides to use this notebook to kill criminals and improve society. Eventually, a combination of hubris and desperate attempts to avoid capture lead him to betray his original morals. Kids who watch Death Note tend to focus on how badass they think either Light or his detective opponent L are. Yes, L is badass (Light isn't, sorry guys) but the biggest hook for grown-up viewers is the major question posed by the series: does any one person truly have the right to decide who lives and who dies?
Death Note is a classic example of an anime that poses moral questions, but it's far from the only one. Another good one is Psycho Pass, which features the Sybil system, a series of tests that analyze your personality, your mental and physical health, your genetic heritage, and other traits to determine your station in life. Viewers of Psycho Pass have to grapple with the concept of free will. What does it mean? Is it real? Are our choices actually determined by traits we don't control? How does free will factor into the creation of an ideal society? These are not questions targeted at kids.
The kinds of food we choose to put into our bodies is actually a pretty serious issue, and not just in terms of our personal health. How far will we go to ensure our own survival? What about our own personal happiness? What kind of consumption makes you a monster? These aren't issues kids are necessarily ready to consider.
That said, there are some really interesting adult-oriented anime out there ask these kinds of questions. Tokyo Ghoul, which is explicitly violent enough to disqualify itself as a kids' show already, is one example. "Ghouls" are humanoid creatures who cannot survive without eating human flesh. Often, this means being forced to take human lives. As viewers watch Kaneki, who has been surgically transformed into a ghoul against his will, struggle to accept his survival needs, we have to ask: is it really wrong for ghouls to kill? Is it different from humans killing cows, chickens, and other animals for our own survival?
On the flip side of this, we have The Eccentric Family, an anime about the conflict between humans and mythical creatures called tanuki and tengu. The tanuki patriarch of the Shimogamo family, Soichiro, was eaten alive by a group called the Friday Fellows. To the tanuki characters, this is terrifying, but to the humans, it's a joyful tradition that brings them together and gives them the chance to appreciate a unique food. Whose perspective is right? Can both be? Is consumption appreciation? If you love something and destroy it, is that still love?
There questions aren't easy to answer, and The Eccentric Family doesn't attempt to do so definitively. Like Tokyo Ghoul, it forces viewers to think seriously about their own food choices in a way that's unlikely to resonate with most kids.
Death is one of the most difficult concepts human beings have to grapple with. Most adults aren't completely at peace with the fact that they and their loved ones will die, so you can't really expect kids to be ready to handle the idea.
That said, death is rampant in anime. Some shows focus on a single death, and how it impacts those left behind. In Anohana: The Flower We Saw That Day, a little girl named Menma's untimely, accidental death traumatizes her friend group, and forces them to confront some harsh realities. In Free! Iwatobi Swim Club, Rin's whole character arc centers around his grief over the death of his father. In Erased, the main character's mother is brutally murdered by the end of the first episode.
Other shows deal with death en masse. Countless people are slaughtered in Attack on Titan, more people die in Death Note than a Shakespearean tragedy, and Puella Magi Madoka Magica makes Homura, and by extension the viewer, go through Madoka's death hundreds of times. No kid needs to see that, that's adult content.