The Master of Ragnarok & Blesser of Einherjar (Manga) Volume 5 by Seiichi Takayama

Yuuto's new Nordic life isn't the Hygge-filled heaven he may have hoped for. The Wolf Clan face continued challenges from outside, and a tenuous grasp on control by the benevolent, ageing patriarch within. As past memories resurface, Yuuto finds that conquering the discomforts of his modern upbringing could be the source of salvation for everyone involved - but can he turn that information into iron before the next battle begins?