Rectreem is a vaguely mammalian creature, loosely resembling a naked mole rat, with a tree growing out of its anus. The branches present on its head bear a resemblance to the horns of a goat, suggesting Rectreem may be based on a faun, a mythical being with features of both humans and goats. Fauns are associated with nature and forests, hence the Grass typing. It may also be a parody of official Grass-type Starter Pokémon, many of which have vegetation growing on seemingly unfavourable parts of their bodies. Its evolutionary line may also evoke the phrase "a stick up the ass". Much of its body is composed of its backside. Its shiny colouration is based on a blossoming cherry tree, or sakura.
Rectreem is a combination of the words rectum and tree.
Benpirin is a combination of shinrin (forest) and benpi (constipation).