No, this isn’t a mod or a prank, Nintendo has officially added the character Chitoge Kirisaki from the anime and manga series Nisekoi as a Mystery Mushroom costume for Super Mario Maker. Like all other Mystery Mushroom costumes, the Chitoge costume acts as a replacement for the Super Mushroom power-up and transforms Mario into that character. Due to technical details, Mystery Mushroom costumes are only available to use on levels using the original Super Mario Bros palette. Unlocking the costume is a simple matter of completing either one of two event courses that Nintendo has released freely for all players in all regions. Nisekoi is a romantic-comedy where Chitoge and the male lead, Raku Ichijo, absolutely hate each other, but are forced into a relationship by their gangster fathers to make peace between their criminal organizations.
Guest characters are nothing new to Super Mario Maker as Chief Arino from popular gaming show GameCenter CX and Felyne from the Monster Hunter series have been added in the past. What makes Chitoge’s inclusion unexpected is that the Nisekoi series has no preexisting relation to Nintendo or the Mario franchise. There has been a Nisekoi visual novel, but it was developed by Konami and released exclusively for the Vita. This crossover is most likely the result of a sponsorship deal similar to the ones previously made with Mercedes-Benz and Southwest Airlines. Either that or someone at Nintendo is an insanely big fan of the anime.
You can check out the official reveal trailer for Chitoge Kirisaki here. Who do you think could be the next out-of-nowhere guest character to appear in Super Mario Maker? My money’s on sci-fi slasher film icon the Predator. Between Call of Duty: Black Ops III and Mortal Kombat X, that guy is appearing in everything these days.