Number 4: Stealth Kragen

Number 4: Stealth Kragen was introduced in the Maze of the Master booster set as part of the Yu-Gi-Oh! Official Card Game's ongoing Number series. These cards were originally conceptualized for the Yu-Gi-Oh! Zexal anime, where 'Number' monsters represent powerful, spectral entities that possess unique, game-altering abilities. The design intent for the Kragen series was to emphasize a water-based, tactical archetype that could manipulate the field by altering the attributes of opposing monsters.

The card was illustrated with a focus on its aquatic, mechanical aesthetic, reflecting the high-fantasy sci-fi blending typical of the series' character designs. Upon its release in the English-language TCG, the card was received as a niche but effective tool for decks utilizing WATER attribute support. Its reception among the player base centered on its disruption potential, particularly its ability to turn all face-up monsters on the field into WATER attribute, which synergized well with existing control-based strategies.