Psychological torture scenes are among the highest intensity and alarming ones out there. While most such scenes focus on inflicting physical harm, others are more focused on the victims' mind.
Many anime characters who experienced psychological torture are at the mercy of their enemies' supernatural abilities. When Mob Kageyama is forced to live through a grim fictional existence where he's being severely bullied by his classmates and has no power with which to defend himself, this is entirely due to Mogami's psychic powers. On the other hand, some examples of psychological torture are fairly down to earth. While much of the physical torment that Jason visits upon Ken Kaneki is impossible without magic, the psychological burden of being forced to choose what lives Jason should take - no magic involved.
Which instance of psychological torture disturbed you the most?
At the end of the first season of Tokyo Ghoul, Ken Kaneki experiences a potent blend of physical and psychological torture at the hands of Yakumo Oomori, aka Jason. The physical pain is absolutely horrific - a centipede is placed in his ear, his fingers are repeatedly lopped off so that they can regenerate and be lopped off again, and more.
This isn't enough to break Kaneki, so he decides to emotionally traumatize him instead. He gives Kaneki a choice: should Oomori end Kouto's life, or Kei's? When Kaneki is unable to choose, Oomori eliminates them both, all while doing his best to ensure that Kaneki knows it's his fault that he's doing this. This event, combined with some intense internal experiences involving a conversation with Rize and uncovering repressed childhood trauma, lead him to embrace his inner ghoul and discard his formerly peaceful persona.
Just about everything in Hellsing is violent to an extreme and the instances of psychological torture are no exception. When Seras Victoria faces off against Zorin Blitz, she finds herself forced to hallucinate some of the most graphic and terrifying sights that anyone has ever had to witness. Zorin makes Seras relive the worst memories from her past, which include her parents being taken out by gang members and her mother's corpse being violated afterward.
While Seras is distracted, Zorin takes the opportunity to lop off her arm and slice her eyeballs. She's only able to recover when Pip begs her to drink his blood before he himself passes, which she does - thus turning her into a vampire who is 100% capable of ending the conflict.
Just about everyone in Fruits Basket is the victim of some form of psychological torture, but for now let's focus on Yuki Sohma's experience, as it's one of the more compressed ones.
In order to gain favor with the family head, Yuki Sohma's mother essentially gave him to Akito when he was a young child and Akito was a slightly older child. Because Akito was suffering from some severe trauma of their own, and because Akito genuinely felt that Yuki was property, things quickly escalated into torture territory. What begins as Akito issuing mild complaints turns into Yuki being locked in a tiny room for days at a time while Akito screams about how the world is an absolute nightmare.
Yuki is so broken down by this that it takes a toll on his health - his asthma flares up, and he can barely leave his bed. He only gets out when Shigure finally rescues him at Haru's urging.
As if learning that his formerly beloved brother Itachi had eliminated every single member of their clan wasn't bad enough for 8-year-old Sasuke, Itachi just had to make things infinitely worse with his Tsukuyomi technique. Sasuke wasn't present for the massacre itself, which meant that he could have avoided the direct trauma of doing so, but Itachi forced him to not only see the events but also replay them ad nauseam until they were permanently cemented in his mind.
Itachi's intention was to make Sasuke despise him enough to eventually come after him, which may be why he chose such a cruel method.