Boruto: Naruto Next Generations 84. Bölüm (Oonoki's Thoughts, Ku's Thoughts)

Boruto and Oonoki head to the rendezvous point, but they stumble into the Hidden Stone Shinobi Training Grounds, which are protected by a barrier. Oonoki tells Boruto that the only way out of the Training Grounds is to find his heart of stone, something that can only be found once in a lifetime when a person comes to terms with their will. (Source: Wikipedia) Mitsuki's Disappearance Arc: (14/22)