Seijo Shoukan ni Makikomareta Omake Joshi, Shota Majutsushi no Kaseifu ni narimasu

In a magic spell gone awry, two saints are summoned instead of one! Of the two girls who appear in this other world, the plain-looking Sayo is cruelly rejected by the kingdom's prince. Despite being brought there against her will, Sayo is deemed unwanted and put to work as a servant in the castle. One day, she happens upon a gate in the forest. On passing through, she encounters a large, fluffy beast and an ill-mannered but handsome boy mage...! In the mage's tower at the farthest reaches of the kingdom, Sayo is comforted by the fluffy beast as the mage proceeds to make her his plaything. Her new life as a maid in another world is about to begin... (Source: Renta!)