Cube Arts manga volume 2 features story and art by Tomomi Usui.

Takuto, trapped in a sandbox-style video game, must save his friend Noa from slavery. So he crafts the Iron Greatsword, a powerful weapon made of diamonds. Meanwhile, the truth behind the Soul Stones that drop when a player is killed begins to emerge. Minecarts, monsters, mayhem…in this cubed world, the possibilities for fun—and death—are endless!