Marriagetoxin

is a Japanese web manga series written by Joumyaku and illustrated by Mizuki Yoda. It has been serialized in Shueisha's Shōnen Jump+ app and website since April 2022, with its chapters collected in 16 volumes as of January 2026. Viz Media licensed the series for English release. An anime television series adaptation produced by Bones Film is set to premiere in April 2026.

==Plot== Hikaru Gero is a young man from the Poison Clan of professional assassins, which has been in existence for hundreds of years. Because he deals in the dark side of society and has never lived a "normal life", he considers himself to have no prospects with women and has no interest in marriage. However, one day, the Poison Clan states that if Gero does not marry and produce an heir to carry on their lineage, they will force his sister into bearing a child against her wishes. Wanting to save his younger sister from such a fate, Gero asks one of his assassination targets to marry him. When the cross-dressing marriage swindler Mei Kinosaki declines, Gero instead has Kinosaki train him to date and how to appeal to women with the goal of finding someone he truly wants to marry.