Born October 31 in Sta. Ana in Manila, Philippines. His mother, Magdalena de los Santos dies when Castrillo is a year and a half old. A fertile imagination begins to reflect in the toddler who remembers dreams, sees forms and figures on cracks and wood grains of empty walls. He takes pieces of marble, plays with reflections of the sun and visualizes forms inside the marble pieces.
Enrolls at the Ateneo in Padre Faura but drops out to finish gradeschool at the Sta. Ana Elementary School. He begins to draw figures on corners of notebooks, that, when skimmed in sequence, produce animation. He begins to fashion toys from tin cans. A fascination with the metal's warped surface begins.

HIGH SCHOOL
1950s until 1963

Joins a cumbanchero group caroling, singing and acting in street corners. He helps his father, Santiago Castrillo, a local community leader and master craftsman, prepare the papier mache creche or belen every Christmas. Inspired by his father, Castrillo would later donate his designs to the community for Christmas pageants and holy week festivities.

A need for solitude and bouts of depression begin to appear. He attempts suicide three times. He is brought to Don Bosco School, where, under the guidance of the Don Bosco brothers, he learns formal techniques of craftmanship. He designs liturgical art, does engraving and retouching of bronze sculptures. He is one of a group of young men sent to assist in the restoration and renovation of the altar of the Manila Cathedral under Rufino Cardinal Santos and consultant artist, Galo Ocampo.

UNIVERSITY

Enters the University of Sto. Tomas' Fina Arts School as a Don Bosco scholar under the financial support of Don Antonio Delgado. He becomes a working student but does not take school seriously. Joins a band called the "Erratics" as drummer. He befriends all the gangs around Manila and galivants.
Works at a variety of part time jobs: rewinding motors at an electrical shop, repairing typewriters at Smith Bell and Company, as an elevator boy in an Escolta office, and as an illustrator of comics on the side.