Eight Trigrams Sealing Style

* Name:
 * Type: Fūinjutsu, No rank, Supplementary, Short range (0-5m)
 * Users: Minato Namikaze, Hiruzen Sarutobi
 * Debut (Anime): Naruto Episode 1
 * Debut (Manga): Naruto Chapter 1

The Eight Trigrams Sealing Style consists of two Four Symbols Seals, increasing the power of the seal. After the Death God pulls out the soul of the victim during the Dead Demon Consuming Seal, this sealing style is used to actually seal the victim.

When Minato Namikaze used this sealing style to seal the Nine-Tailed Demon Fox, he left a space between the the Four Symbols Seals, allowing the demon fox's chakra to merge with that of the seal's medium, Naruto Uzumaki. However the 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.

Trivia

 * This appears to be the only Eight Trigrams jutsu that has nothing special to do the the Hyuga Clan