As a genre, psychological aims to reach your psyche, where your conscience and perception of reality lies. There's not so much a focus on gore (though Tokyo Ghoul has its fair share), as there is on questions like: What makes us human? What doesn't make us human? and What disqualifies us from being human? Psychological distorts our sense of reality and tears us down, from a moral and ethical standpoint. There's a number of great psychological manga out there, outside of the masterpieceDeath Note, that is.
1.) Oyasumi Punpun
Any work by Asano should be labeled a 'must-read,' because every one will hit you at your core. Oyasumi Punpun itself has a fairly large fanbase, with near everyone claiming they couldn't keep the volumes down. A coming-of-age story, we follow Punpun Onodera as he enters his teenage years and then adulthood. Asano is hardly afraid to touch on less-than-savory topics (such as rape, family issues, and the darkness in depression and mental illness), yet each struggle helps us relate to Punpun one way or another.
Asano's art style is another reason to read this series. It's quite distinct and drawn with loving care, as there's no detail lacking. The symbolism in Oyasumi Punpun is also very distinct from other artists and authors, as its so central to the story. The symbolism of Punpun's design, after all, maps his maturity--though depression, reclusiveness, and all-around emotional hardship mars that very path.
2.) Annarasumanara
Do you believe in magic? Perhaps you will after reading Annarasumanara, a Korean web-comic by Il Kwon Ha, though a masterpiece of the psychological genre nonetheless. In Yun Ai's high school, there's a rumor about a strange magician living in the abandoned amusement park. It's said that he can make anyone disappear without a trace, but not before asking, "Do you believe in magic?" quietly and just to you. Struggling to take care of her younger sibling, nevermind herself, when a precious $10 note flies out of Yun Ai's hand, she chases it all the way to the abandoned amusement park.
Unable to live the frivolity of childhood, Yun Ai experiences the fleeting innocence with the help of L, the strange magician. The dreams, aspirations, and thoughts she could never entertain before suddenly seem possible as she escapes from reality. However, reality always comes crashing back down and neither Yun Ai nor her precious magician are strangers to the feeling.
Like Asano, Annarasumanara implements noteworthy symbolism in its art. Expert use of color amidst the traditional black-and-white pages, implementation of 3D, and character designs lead to a magical experience for us as well.
Original web-comic (in Korean) can be found here, while the translated version by Naver can be found here. Unfortunately, there is no way to purchase Annarasumanara, but that could change in the future.
3.) Me and the Devil Blues
Blues singer Robert Johnson isn't solely a legend because of his music. Robert Johnson is also famed for supposedly making a deal with the Devil at a crossroads right at the witching hour. According to legend, Johnson gave up his soul for skill. Hiramoto explores that story in Me and the Devil Blues, and the troubles that Johnson (could have) experienced as a result. On top of the phantasmagoric elements (including body horror, meantal breakdowns, and a warped perception of reality), Hiramoto also details upon racial tensions and other historical figures (like Bonnie & Clyde). This unreal telling of Robert Johnson's story gives Hiramoto the chance to rewrite history, but with a large dose of horror and psychological thriller on top.
As for the art, Me and the Devil Blues exhibits fantastic skill. The anatomy, action scenes, and facial expressions are perfect. The shading and coloring make pure artwork. If anything, you will enjoy Me and the Devil Blues because of the art alone.
4.) Homunculus
A middle-aged man named Susumu Nakoshi, once an average office worker, now lives out of his car. He's soon approached by Manabu Ito, a medical student, to undergo an experimental operation called "trepanation" in exchange for money. If Susumu undergoes trepanation, Manabu will drill a hole into Susumu's skull, and Susumu will then forever have something akin to an awakened sixth sense.
True to form, Susumu begins to see 'homunculi' or humans, but warped to appear as their worst fears and unhealthiest obsessions. With his perception of the world and the people around him altered, Susumu himelf begins to change. Unsure of where he actually fit in society before, Susumu now actively seeks to befriend these individuals and help them face what troubles them.
Like the works previously mentioned, Yamamoto is a great artist, who puts detail into his landscapes and his characters. The symbolism behind the homunculi forms is also not to be lost.
5.) Liar Game
As the title suggests, in this world there is such a thing as the "Liar Game," and Nao Kanzaki (as her name suggests) is too stupidly honest to come out unscathed. Fearing for her life and desperate for help, she hires Shinichi Akiyama, a renowned swindler recently released from jail. As the Liar Game is full of the darkest parts of a human's soul--greed, deception, selfishness, lies upon lies--Kaitani details upon the worst humans are capable of.
However, he gives us the complete opposite in the form of our narrator. With Nao being innocently honest in the world of such corruption, Kaitani highlights the darkness within Liar Game. We also watch Nao grow into a stronger character as she faces the challenges in front of her. Another noteworthy aspect of Liar Game too, is that the motivations of characters aren't as they seem. Like Death Note, we have to question our own morals and beliefs while reading Liar Game.
In regards to the art, it's not the best, but it does get progressively better as the series continues. However, don't drop Liar Game if the art turns you off at first--this is a must-read if you're a fan of psychological manga!
Unfortunately, there isn't an official english translation of Liar Game to be purchased.