This barrio’s was supposed to have been derived from the Tagalog phrase “mala in-in,” meaning “not well-cooked.” This probably referred to undercooked rice. The barrio’s earliest settlers were the Magnaye, Guerra, Pansoy and Pasia families. Farming was the chief preoccupation of the barrio’s inhabitants and sugarcane was the primary crop. During the Japanese occupation, people of the barrio suffered from food shortage and punishments doled out by the occupying soldiers. Many houses in the barrio were also burned. Travel became difficult after the destruction of the Malainin Bridge.
Malainin is situated at approximately 13.8314, 121.1212, in the island of Luzon. Elevation at these coordinates is estimated at 138.7 meters or 455.0 feet above mean sea level.