|Deadly Stem Force|
|Abilities||Fast Regeneration, Body Distortion, Propagation|
|Manga Debut||Chapter 201|
|Anime Debut||Episode 123|
The Death Stalk Unit is a group of four heavily muscled creatures (formerly humans) that are controlled by Iris.
In the manga, they are four scientists, members of Millefiore's Research Facility, that have experimented on themselves to impress their assistant, Iris, and their object of affection. As they experimented more and more, they turned into mindless monsters that only heard and obeyed Iris.
The anime takes on a more moderate view, as the Death Stalk Unit were not formerly human, but artificial creatures. They were monsters created by the four scientists, who decided to experiment after being encouraged by Iris. The first prey of the Death Stalk Unit was these four scientists who created them, as Iris betrayed them.
- Propagation: When Iris whips the Death Stalk Unit with her Cloud Whip, the monsters are able to propagate their bodies, allowing them to grow and, in the same sense, regenerate rapidly.
- Muscle Scrum: All four monsters combine their bodies in order to make a bigger monster that has much more effective attacks. It was used as a defensive wall by Iris, but it couldn't withstand Tsuna's completed X-Burner.