Pias, sometimes translated as Pierce, serves as the elf mage in the main adventuring party. Her magical abilities require recharging via sexual activity, often involving the barbarian warrior Bobo, establishing an ongoing physical relationship between them. This dynamic shifts when Pias becomes pregnant with Bobo's child during the manga's events, an unexpected development given the implied fertility challenges for sex mages. The pregnancy uniquely interacts with magic, allowing the unborn child to briefly negate a power nullifier field despite its early stage. Pias eventually gives birth, and both she and Bobo retire from adventuring to raise their child.

On quests, Pias fulfills tactical combat roles. She employs offensive fire spells, notably incinerating a kusarimame slime monster. Her capabilities extend beyond direct damage; she utilizes power-enhancing spells in combat, such as augmenting her abilities before casting a decisive spell to defeat a rapewing monster. Interpersonal tensions occasionally arise within the group, like when she and Pink were subjected to voyeurism by Santa and Bobo during bathing, prompting her magical retaliation. Credited as a "witch" in OVA openings, her magical specialization consistently aligns with combat support and offensive applications.

Her relationship with Bobo evolves from casual physical arrangements into a committed partnership after her pregnancy. Both explicitly express joy upon learning of the pregnancy, contrasting with typical genre expectations. Their story concludes as they leave adventuring life behind to focus on parenting their newborn, marking a definitive end to their group involvement.