Super Caffeine

From Kokorodatabase

Super Caffeine (超カフェイン Chou kafiin) is a creation of Kitenshi Kocha. An extra-strong caffeine generally blended into coffee, one cup is known to make the user stay awake for 53 hours. Kocha doesn't see any problem with this, but Ryou finds it disturbing, even as he searches for ways to stay up almost constantly.

A later variant is Super Milk (超牛乳 Chou gyuunyuu), which is supposed to put the user to sleep for 53 hours. So far, in its testing stage, it's only managed one night.