Marisa Stole the Precious Thing refers to a legendary 2006 Flash animation and music video by the dōjin circle IOSYS, based on the Touhou Project series. The song is a high-tempo remix of Alice Margatroid’s theme, 'The Doll Maker of Bucuresti,' and became a foundational 'denpa' song of early internet culture on platforms like Niconico and YouTube. The phrase originates from the lyric describing the character Marisa Kirisame stealing something valuable from Alice—implied to be her heart or her 'precious thing.' It is widely used to humorously describe situations where something important is missing or when a person has been captivated by another. The meme remains a nostalgic symbol of mid-2000s otaku culture and is frequently parodied with various characters replacing Marisa and Alice.