From Seven Seas:

Tor Kokonoe has entered the prestigious Koryo Academy, a high school dedicated to training its students to wield Blaze―individualized weapons that a student manifests. The future of a student is often shaped by the form their weapon takes, and when Tor’s appears as a shield, suddenly he’s the odd man out. But that’s when the Duo system comes in, a program where students are paired up. Teamed up with a silver-haired girl named Julie Sigtuna, Tor’s adventures at Koryo Academy are just beginning!