In this world, people are born with a special nerve in their right arm that connects to their heart and allows mana, a type of energy, to flow into it and strengthen their arm. Some of the mana also scatters throughout the body, making it stronger overall. However, every few years, a person is born with the nerve in their left arm instead. These left-handed people are often shunned and not accepted by society. The main character, Shina, was sadly born with a left-armed nerve and faced rejection throughout her life. Only after reaching the grandmaster level was she finally accepted. She tried to change how society viewed left-handed people and was close to succeeding, but she was assassinated. However, her journey wasn't over, as she found herself regressing to childhood. Determined to succeed this time, she vowed to make a difference in the world. [stages of power. Commoner, Trainee, Mercenary, Warrior, Knight, Master, Grandmaster, Demigod, God.