Bujins are an Tri-Beast archetype that heavily focus on control. Their Xyz monsters have powerful effects, they can add or send "Bujin" monsters from your Deck, mill 5 from the top of your deck, recur banished resources, or even reset your hand.
The Main Deck Beast-Warrior Bujin monsters are your vanguard, the front lines, the monsters that stay on the field and protect you, while the Beast and Winged Beast Bujins provide interaction in the hand and GY respectively to support and disrupt.