Danzer, an old man who had been participating in an A-rank party as a baggage carrier, was one day used as a decoy by Zairos, the party's leader, and devoured whole by a Divine Dragon.

Within the Divine Dragon, there was neither food nor water. All that existed was a pale pink wall...the Divine Dragon's wall of flesh. So Danzer filled his stomach with the Divine Dragon's flesh he stripped from the wall of flesh, and quenched his thirst with the Divine Dragon's blood that gushed out as he stripped it. After 189 days spent within the Divine Dragon in this manner...his body had transformed into a Lizardman.

Furthermore, it appeared he was no ordinary Lizardman; his scales had become equivalent to the Divine Dragon's scales, his blood to the Divine Dragon's blood, and his eyes to the Divine Dragon's eyes. Though perplexed by his grotesque new form, he rejoiced at having obtained the 'strength' he had yearned for since childhood, and vowed to use it righteously.

Now, it begins. The heroic tale he had always yearned for.

...Though the protagonist is a Lizardman.