3mix (Nayeon, Jeongyeon and Jihyo) is the friendship trio and they were in the pre-debut group 6mix.
Before debuting as Twice, Nayeon, Jeongyeon and Jihyo (then later Sana) were supposed to debut in a 6 members group 6mix. However, the plan was cancelled due to Lena and Cecilia's departure of the group.
The 3 of them went through many obstacles together before debut, which leads them to a strong bond of friendship.
They rely on each other the most.
They have their own friendship bracelets which they still wear.