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The Kuchiyose no Jutsu or summoning technique has a variety of forms, depending on who’s contract you sign or your lineage. In Minato’s case, he signed a contract with the toads, becoming the fifth person to have the ability to call upon a toad from the spirit world.

This technique was granted to him thanks to Jiraiya, the current moderator of the contract. In taking part of this agreement, one signs their name and leaves their with their own blood. This fully grants them the power of summoning. Weaving the signs for boar dog bird monkey ram and drawing a bit of their own blood, a toad of various size will be summoned, in relation to the amount of chakara used to perform the jutsu. The largest toad that can be called is Gamabunta, the boss toad, which Minato is first seen with going off to face the Nine Tailed Fox.

Not surprisingly, Naruto Uzumaki also learns to summon the toads, taking three weeks to learn how much chakra it would take to summon Gamabunta. The boss toad notes that no one had summoned him since Minato, indicating that in general, he is only summoned at times of great need.