Marriage Toxin manga volume 3 features story by Joumyaku and art by Mizuki Yoda.

Gero pushes his assassin skills to the limit when Kinosaki signs him up for the job of bodyguarding Shiori Ureshino, the daughter of a high-profile CEO. He’ll need to go toe to toe with Sound Master Naruko, a rival assassin, in order to protect Ureshino and prevent Naruko from turning her university camping trip into an all-out horror show!