Raise wa Tanin ga Ii

Both stories revolve around intense, unconventional romantic relationships set in dangerous, morally complex worlds. Both series place their characters in life-or-death situations, with the danger inherent to their worlds deeply influencing their relationships.Themes of loyalty, survival, and trust play central roles in both stories. Both series incorporate action-packed sequences, often juxtaposing moments of tenderness with brutal violence. 

Both center a tough, pragmatic female lead who can hold her own, and shows little interest in the man romantically pursuing them. The male leads introduce problems the female lead has to contend with to push the plot forward. Each has dealt with a power imbalance in the relationship and the tension that it creates. Apothecary diaries is more of an external mystery focusing on medical and political cases, while yakuza fiancé is more of a psychological mystery focusing on understanding the characters– particularly Kirishima.  

Both revolve around protagonists who are "granddaughters of yakuza." A lot of other similarities as well! 

Both female leads have multifaceted personalities that go beyond surface impressions. Holo and Yoshino have strong inner resolve. They’re confident, clever, and unafraid to assert themselves. Both stories explore relationships in unique and unconventional settings, their tones and narrative approaches are distinct. Spice and Wolf is more philosophical and warm, while Yakuza Fiancé is darker and more dramatic.  

Both anime have a main female character that comes from a yakuza family but are down-to-earth and don't want to be in the world of the yakuza but when push comes to shove they show their badass side. Both anime have a highschool setting that mixes with the yakuza setting, Gokusen has the female MC be a highschool teacher and Raise wa has the female MC be a highschool student in her final year of school. Both anime have the male leads be difficult to deal with and they also like to resort to violence (especially Raise wa's male lead Kirishima) but they both end up admiring the badass, no-nonsense female MC. read more 

A gritty crime drama with intense relationships. 

Both anime have badass female protagonists that are involved in the world of organized crime, Revy in Black Lagoon and Yoshino in Raise wa. Yoshino is the granddaughter of a yakuza boss similar to Yukio Washimine from Black Lagoon: The Second Barrage who is the daughter of a yakuza boss while Revy is a gun for hire that many times works for the mafia. Both Black Lagoon and Raise wa have strong but crazy, mentally unstable characters, in Black Lagoon those type of characters are mostly the women while in Raise wa those types are mostly the men.