Plant-kun is a fern-like potted plant that formerly resided in the living room of the Ten'ou House. It is incredibly resilient and has recovered from massive damage that would have finished lesser plants. Plant-kun is an avid fan of Barry White music. It has previously had romantic encounters with several individuals, in particular Viney-chan. Plant-kun's leaves are an incredibly potent substance, and can have a wide variety of mind-warping effects which vary by the individual. In an alternate version of reality, Plant-kun is instead Tree-kun.
Since a chance encounter with Sakurazukamori, involving a pending knife fight, Plant-kun has since been relocated to the assassin's secret greenhouse.