Known as Migatte no Gokui in the original Japanese, it is a state of being introduced in Dragon Ball Super, where its user can react without the need of acknowledging and subsequently thinking about the threat at hand - an ability so notorious for being exceptionally difficult to master that even the gods struggle to achieve it at times.
Son Goku is shown accessing the ability - first in an incomplete state (-Sign- or -Omen-) and later in a perfected state - though not retaining it afterwards. In the former state, his body receives a blueish aura around it, his hair becomes slightly spikier and his eyes become silver-colored; in the latter form, alongside the previous additions, his hair becomes fully white and his hair becomes slightly more wild. Later, it is revealed that perfected Ultra Instinct can manifest a ki-based Giant form.
