Shadow Skill

Gau Ban is a boy who is struggling to become a "Sevalle," the strongest class of warrior in the mercenary kingdom of Kuruda. Gau's elder sister, Elle Ragu, is the 59th "Sevalle" and holds the honorable title of "Shadow Skill." The story develops around the two siblings, as they fight magical monsters and historical warriors. The major part of it is a battle called "Shadow Skills" that is fought with only the hands and feet. It begins when the historical warriors chant the words "We are invincible!" and obtain superhuman powers. Note: Originally published by Takeshobo and continued by Fujimi Shobo in Monthly Dragon Jr. This material was later collected by Kodansha in 3 Aizoban volumes before a new series began in Afternoon, running for another 11 volumes, with the volume numbering restarting.