Yoriko Yasaka (八坂 頼子 Yasaka Yoriko?) is Mahiro's mother, a real monster hunter who started her career during college. She has a young appearance that makes it hard to believe that she has a son in high school. She conceals her true job from her son until returning home during the plot. She is kind to friendly aliens, accepting Nyaruko, Kūko, and Hasuta living in the house, and their actions to pursue Mahiro. She advises Nyaruko to take her relationship with Mahiro a bit slower at first, but permits their relationship later after they rescued her. Just like her son, she uses throwing forks as her main weapons, being better skilled and able to carry more "ammo" than him. She is obsessed with video games, buying different game machines whenever she returns home from hunting. She also has a ha