Tooru Kokonoe, seeking strength to avenge his sister Otoha, manifests a shield instead of a weapon as his soul-born Blaze and is branded an 'Irregular' at Kouryou Academy. Paired with Julie Sigtuna, a vengeance-driven transfer student from Scandinavia, he starts training as her combat partner while the two share a dorm room neither entirely trusts. The manga adapts the Absolute Duo light novels.