Ai no Kusabi (2012)

Both focus on male sexual abuse, powerful mobs, and the gritty underside of society. Ai no Kusabi is sci fi while Banana Fish is modern New York. Both have infuriating endings. 

Ai no Kusabi and Berserk both contain the same themes of the darkness of the human heart and karma. They also have a massive amoints of sex and violence, but Ai no Kusabi has less violence but still the same brooding atmosphere as the second Berserk movie. Not only are the animation designs very similar as well, they both have great animation and a great cast of characters. 

Mirage of Blaze is a unique anime that is similar to AnK but at the same time rather dynamically different. If you enjoy BL anime where the two main characters are constantly ‘clashing’ against each other and thus creating a sort of love/hate relationship with a huge dose of drama then give Mirage of Blaze a try. The relationship development in MoB is far more subtle than in AnK so take heed if you are not a fan of historical dramas and lack the patience to endure through a slow paced story. However MoB is worth watching, if you are unsure whether you will like it give it a try first.  read more 

Yami no Matsuei, Ai no Kusabi, and Mirage of Blaze makes up the three classic triads of this type of BL anime. To start off Yami no Matsuei is similar to AnK in that the main antagonist is very similar to Iason in both possessiveness and obsession over their ‘love’ interest, but at the same time both have ‘to die for’ looks that makes it impossible for you to hate them. Both these anime unfolds into a complicated plot that keeps you absorbed by the conflict – which usually involves some kind of drama between said main characters – and the story arc ending will leave you in a pretty satisfied condition. If you are a fan of AnK watching Yami no Matsuei is a must. read more 

Both BL but Ai no Kusabi is more serious when Sekaiichi is more light hearted  

both are dark shoujo stories with a dark, obsessive, powerful long-haired aggressive lover that suddenly enters the main character's life.