Jack-in-the- (びっくり Bikkuri) is an Archetype of DARK monsters created by Taylor Gorrell. Fitting the name, they are all visually based on jack-in-the-boxes. They rely on a Fusion style revolving around the old Fusion Monster, " ".
A Jack-in-the Deck is quite Fusion-reliant, specifically on Bickuribox, which has only 2300 ATK and no effects. However, these card can add what is needed to Summon Bickuribox to your hand easily, recycle Bickuribox should it be destroyed, and can even Summon Bickuribox by completely bypassing the need to Fusion Summon. The higher-Level Fusions all require Bickuribox as a Material along with a "Jack-in-the-" monster of a certain Type: Warrior, Fiend, Spellcaster, or Machine. This makes options rather broad, especially with "Jack-in-the-Mirror's" ability to become any of the four above Types.