Toad is a main character, and member of the literature club from Croaki Croaki Literature Club. She is also a Mario replica of Yuri. The protagonist only likes Toad because of how graceful she is. Steve Mckoy 11 (Onee - san Inc.), couldn't think of an amphibian/name parody so he used a Mario character which is Toad. Toad is instead a female, purple mushroom headed version with an iconic Toad outfit.
Toad is instead a female, purple mushroom headed version with a purple gold outlined jacket and white shorts. If you want to know Monika's appearance from the DDLC game, it's right here: https://doki-doki-literature-club.fandom.com/wiki/Yuri#Appearance.