The world of seinen manga is a rich and diverse one, offering the complex storytelling that shonen titles often shy away from. The main difference between seinen and shonen is the level of emotional complexity. As opposed to the perennial shonen do-gooder, seinen leads can be conflicted and indecisive, hurting as much as they help, with many being morally ambiguous anti-heroes. Seinen has no obligation to provide a happy ending, and the tragedies protagonists must face opens the door wide for emotionally layered stories, ones built on more than action or comedy. In terms of American fiction, for example, Spider-Man and Superman would be shonen, while the Punisher and Batman would fall into seinen.
Seinen manga doesn't have to be R-rated, but it's often at least PG-13 in content, and a lot more material is fair game than for shonen. Seinen titles often have graphic violence, body horror, psychological horror, sexually explicit material anything else one might consider "adult." The intent of most seinen is to challenge the reader and, for this reason, the genre is aimed at college-aged and adult audiences, whereas shonen is meant for younger audiences. All the same, many older audiences adore shonen titles, and younger manga fans often find something to like in seinen, too.
Tokyo Ghoul
Sui Ishida's fantasy-horror action series Tokyo Ghoul is a gory, blood-splattered take on the classic shonen paradigm. Its star, Ken Kaneki, is a college student who runs afoul of a flesh-eating Ghoul named Rize, and he barely survives... after waking up as a half-Ghoul himself. Ken walks the line between the human and Ghoul worlds, realizing that both sides have innocent people and monsters alike. For him, it's not as simple as "defeat the Ghouls" or "protect the humans." Ken is on a crusade to protect all innocents from monsters, resulting in some serious line blurring.
Ken lives in a violent, dog-eat-dog (literally) world where justice is delivered one person at a time. As Ken puts it, "this world is wrong," and thus he takes it upon himself to change it. The action is intense and bloody in this series, torture and dismemberment will become familiar scenes for any would-be readers.
Berserk
Berserk is perhaps the most infamous seinen title of all. So infamous, in fact, that its volumes are sold in shrinkwrap to shield unsuspecting eyes from the gruesome displays within. Running since the late 1980s, this manga tells the story of the mercenary Guts, and his bloody path to avenge his comrades, who fell at the hands of their former leader: an all-powerful spirit king named Griffith.
What follows must be read to be believed. Berserk has earned a great deal of attention and praise for its absurdly detailed art and compelling tale of war, hate, love and tragedy. The chapters feature some of the goriest and most heart-wrenching scenes ever found in manga. Fans of Game of Thrones and The Witcher will absolutely want to read this series - if they've got the guts.
Vinland Saga
In the early 1000s, England was under the rule of Vikings. Clans and warriors pillaged and waged war on each other, weaving intricate webs of betrayal and revenge. Vinland Saga draws from this rich well of historical lore to tell its critically-acclaimed tale. This seinen series is ongoing, much like Berserk, sports amazingly detailed art.
The saga is the violent and dark tale of Thorfinn, a young fighter and the son of a slain ex-warrior. This is not an uplifting tale of becoming a hero or a savior or making friends; it is about revenge, one knife at a time, and this series does its best to depict the real life of Vikings. It's not glamorous or uplifting, but Vinland Saga is certainly engaging.
Ghost In The Shell
Seinen manga isn't just a stomping ground for dark fantasy or medieval adventures; it's also a fine setting for science fiction. As a whole, science fiction challenges its audience with tough questions about computer intelligence, the role robots and machines play in our lives, the ethics of mega-corporations, cyber-crime, pollution, and more.
Ghost in the Shell just about wrote the book on all these things, being among the most influential sci-fi series of all time. The series dates back to the 1980s and has been adapted into many forms of media, from the Standalone Complex anime to animated and live-action films. It is centered around Section 9, a high-tech agency that is tasked with fighting criminals and other rogue parties, as well as Major Matoko Kusanagi, a cyborg cop. It's a classic cyberpunk tale that trades in funny robots and spaceship adventures for neo-noir, grimy streets filled with hackers, psychopaths and deadly androids. It's not an optimistic view of the future, but it may prove prophetic.
Elfen Lied
Despite its aggressively anime visuals, Elfen Lied is definitely a seinen series, one whose explicit contents may rival that of Berserk - though the series isn't nearly as long. It blends science fiction and fantasy in a narrative about the Diclonius race, people with horns on their heads and the ability to conjure invisible arms, or Vectors. Driven by predatory instinct, the Dioclonii use those vectors to tear their victims apart.
Mad scientists, nudity, bloody dismemberment, chilling stories of sexual abuse and guns all factor heavily into Elfen Lied, with hapless college students Kouta and his cousin Yuka caught in the crossfire. They are thrown into the world of Diclonii the minute they meet Lucy, a Diclonius with a split personality who's on the run and highly dangerous - they just don't realize it yet.
Seinen manga takes everything a step further than shonen, and for some readers, that's exactly what makes for a good story.