Tsukako no Konkatsu Death Game

Feeling the pressure from the marriage frenzy around her, Tsukako, a 28-year-old single office lady and an otaku, hastily dives into the world of matchmaking. Seduced by the smooth words of Nishikami, a handsome marriage consultant at the agency she rushes into, Tsukako carelessly agrees to a contract stating, "If she fails to marry within a year, her soul will be taken." Shockingly, Nishikami turns out to be a Shinigami (death god)!

(Source: Pixiv Comic, translated)