Zeus no Te

The story revolves around 6 young criminals held in a youth training center. One day a mysterious man appears from the wall. He finds himself wounded and entrusts them with a "hand", which is called "the Hand of Zeus". It harbors a mysterious power and energy. This hand can create a "mouth" that acts like a portal, which they use to escape the correctional room, however having in their possession that "hand" is a great danger, since strange beings are after it so they will have to face them.

(Source: MangaDex, edited)