Marriagetoxin

Poison Master Hikaru Gero is preparing for his most challenging mission yet—getting married! However, after dedicating his life to training as one of the world's most lethal assassins, Gero finds himself completely out of his depth when it comes to dating. Luckily, Mei Kinosaki, an experienced marriage swindler, has all the expertise on love that Gero lacks. Together, this improbable pair will go to any lengths to ensure Gero gets married—even if it means confronting the entire criminal underworld in the process! (Source: Viz) Official English release available on MANGA Plus and Viz (Shonen Jump).