Esper Material

An Esper Material is a card that is currently placed underneath an Esper Monster, either from being used as material for an Esper Summon, or from a card effect. Like Xyz Monsters, when an Esper Monster is Esper Summoned, its Esper Material is placed underneath the Esper Monster instead of being sent to the Graveyard.

Esper Materials can only be attached to Esper Monsters, and Esper Monsters can only have 1 Esper Material at a time attached to them. If an Esper Monster with an Esper Material still attached to it is used as material for an Esper Summon, the material attached to that Esper Monster must be detached and sent to the Graveyard after the new Esper Monster is placed on the field.