Bujintei Kagutsuchi

The monster effect "When this card is Xyz Summoned: Send the top 5 cards of your Deck to the Graveyard. This card gains 100 ATK for each 'Bujin' card sent to the Graveyard by this effect" is a Trigger Effect. (It does not target.)

The monster effect "Send the top 5 cards of your Deck to the Graveyard. This card gains 100 ATK for each 'Bujin' card sent to the Graveyard by this effect" is a mandatory effect that activates when "Bujin Kagutsuchi" is Xyz Summoned.

Even if you have 4 or fewer cards in your Deck when "Bujin Kagutsuchi" is Xyz Summoned, the monster effect "Send the top 5 cards of your Deck to the Graveyard. This card gains 100 ATK for each 'Bujin' card sent to the Graveyard by this effect" will activate. (You send all remaining cards in your Deck to the Graveyard and resolve the effect.)

The monster effect "If a 'Bujin' Beast-Warrior-Type monster you control would be destroyed by battle or card effect, you can detach 1 Xyz Material from this card instead" is a Continuous Effect. (It can also be applied during the Damage Step.)

The monster effect "You can only control 1 face-up 'Bujin Kagutsuchi'" is an effect that is not classified as an Ignition Effect, Trigger Effect, Quick Effect, or Continuous Effect.