Yakuza Fiancé concluded its first season, crafting a highly entertaining romance dynamic. The story combines a few different shojo and dark romance tropes to great effect, mixing popular clichés with more underrated ones. Kirishima is a hilarious yandere love interest; he's toxic, but his darker qualities lend themselves well to a black comedy romance about gangsters.

Yandere love interests rarely take center stage, and many romance and shojo audiences prefer a tsundere or kuudere love interest. Tsunderes can be moody, but they can't hold a candle to a yandere's obsessive, feral nature. Though Kirishima is an unlikely love interest type, his and Yoshino's romance is driven by popular tropes, like forced proximity and arranged marriage.

Yakuza Fiancé Returns to Dark Shojo Romances Dark Romance Comes with a Certain Set of Conventions & Genre Expectations

It seems like there's a demand in the market for dark romance in shojo and seinen anime.