The Master of Ragnarok & Blesser of Einherjar (Manga) Volume 3

Yuuto Suoh faces his toughest challenge yet as the Lightning Clan prepares to invade. Armed with modern tactics and technology from his own time, he must lead the Wolf Clan against the seemingly invincible Steinþórr. With the fate of his allies hanging in the balance, Yuuto must prove that strategy can overcome raw, monstrous power.