Start Card (スタートカード Sutāto Kādo) is a keyword ability that allows a player to put the card with this ability on their own Player Square during the game preparation.
All cards with this ability are Cost 3 Z/X with Power 5000 or less. If a Start Card has another ability, the ability is usually a single startup ability that can only be used if the card in question is in the Charge, and often emulates the effect of an Event with the same Cost as the ability to some extent. For example, "Devil of Vengeance, Ultio" with "Awakening of Devil" or "Handgun Craftsman, Quick Draw" with "Champion's Tremor Spear".
Start Card itself is not a mandatory part of a deck (you may have 0 or more than 1 Start Card in the deck), and a player may choose to not put a Start Card during the game preparation even if they has it in the deck. The current text of Start Card ability is shown below: