Eight Trigrams Sealing Style

The Eight Trigrams Sealing Style, consisting of two Four Symbols Seals, was used by Minato to help Naruto Uzumaki access the chakra of the Nine-Tailed Demon Fox sealed within him. This seal weakens over time. To strengthen the seal again when it gets too weak, Minato drew a key on the abdomen of the scroll toad Gerotora.