Professor E. Gadd's Research Journal

Professor E. Gadd's Research Journal is a serial anecdote published on the official website for the Nintendo 3DS version of Luigi's Mansion. It is a journal in which Professor E. Gadd relates the accidental discovery of a green slimy, "Goo," responsible for the creation of Gooigi.

XXX-001 An Accidental Discovery
E. Gadd begins by making a short introduction on the "strange liquid energy" collected from befriended ghosts, positing that it is "the key to many, many new inventions." However, he explains that he initially struggled to uncover the uses of this energy. His failed experiments with the energy included poking it with iron, pouring it on rubber, and even absent-mindedly dipping a donut into it.

The professor recounts that later during his research, he was scared by a Hider ghost that had escaped from its confinement, causing him to spill the coffee he was drinking into a vial containing ghost energy. He claims that the coffee, described as a "Lunoman Greenie blend from Evershade Valley," quickly reacted with the energy inside the vial, leading to the creation of a green viscous substance. E. Gadd recognized the substance as a new chemical element and called it "Goo," which he then assigned the "00" entry in the.