Kurozakuro (vols. 1-2) by Yoshinori Natsume, translated by Camellia Nieh
Here's a 21st-century spin on the 90-pound weakling who wakes up one day admirably transformed, complete with bulging muscles and confident attitude. That said, check out these covers: this version is not without some menacing twists. "There's something called a 'food chain' in this world....