Musashino Milk (ムサシノ 牛乳 Musashino Gyūnyū) is a Milk brand that was originally introduced in the ToAru Kagaku No Railgun anime adaptation and is later popularly used in the second ToAru Majutsu no Index anime adaptation.
Not much is known about the brand, however, several female characters seem to enjoy the drink in both franchises. Most infamously, it is often associated with female characters with Large Breasts.
The tagline of the product is: "When it comes to milk, it's gotta be Musashino!"
External links
https://toarumajutsunoindex.fandom.com/wiki/Musashino_Milk