One morning, Tateomi Kondo, a young man who tends to be ill, wakes up to find a strange bird-subhuman sister next to him...? Tateomi is revitalized after eating an egg laid by a girl who calls herself Lupia, but the effect is so strong that his crotch is also revitalized. After gently nudging him, Lupia welcomes the egg into her vagina....

(Source: DLsite, translated)