These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Kogan Iwamoto, the head of the Kogan-ryuu Dojo, particularly for his treatment towards women. So great is his cruelty in and out of combat that even the psychotics and pedophiles among his students are taken aback. Indeed, in a series full of depravity and madness, he consistently stands on his own mountain of heartlessness. Two key examples are his treatment of his daughter, Mie. He wanted a son instead and only sees her as a vessel for carrying the dojo's heir. Thus, he's willing to watch her get raped by one of his students to make sure she got pregnant, slashed through a student's face for suggesting she should have a husband that respects her, and scoffed at her mother committing suicide when Mie finds her body. When the man first picked as Kogan's successor, Irako, is cast out, she spends years starving herself, eventually reducing herself to a semi-sane bag of bones. He only shows concern once he realizes she won't be able to give birth in such a state, and he almost rapes her himself. As for his concubine Iku? She was seen as cursed by the locals, as every man she gets involved with dies in one way or another. Thus, she is grateful to Kogan because he was kind to her despite that...until one of his top students, Irako, tells her that Kogan killed her first husband just to show off a sword technique. She and Irako become lovers behind Kogan's back; when he finds out, he slices off both her nipples, mutilates one of her breasts by burning it, and then blackmails her into burning a hole through Irako's penis. Oh, and this is AFTER Irako is tricked into getting beaten to a pulp by his fellow students, but BEFORE Kogan personally blinds him by slicing his eyes open.
Whole Plot Reference: A quiet and reserved warrior forms friendship with beautiful and ambitious warrior. The latter, however, makes a very wrong choice because of his ambitions and ends up brutally mauled. He overcomes his new-found handicaps and slaughters everyone involved in his ordeal. A reserved warrior is mad with ambitious warrior and swears to kill him. The first time he tries it, he loses a hand. It's Berserk.