The Green Hollow Pen.

A Hollow Pen (ホロウペン) is a pivotal item in Time Hollow that can be used to dig holes into the past. Ethan Kairos gains one on his 17th birthday during the Prologue.

Hollow Pens "use" the time of whoever uses them; it ages the user at a faster rate physically. Only two Hollow Pens have known to exist:

  • Green Hollow Pen: The family heirloom of the Karios family. It gets passed to the eldest heir when they reach age 17.
  • Red Hollow Pen: Belonged to the Onegin family.