Kara no Kyoukai 7: Satsujin Kousatsu (Kou), Fate/stay night: Unlimited Blade Works 2nd Season Recommendations
Both series were performed by ufotable
Both were written by Kinoko Nasu and take place in very similar universe.
Their characters using mystical and magical powers.
Both animes have a romance between the two main characters (Shiki-Kokuto / Shirou-rin)
Both animes are very dark, violent and psychological.