Sozo Renkinjutsu Shi Ha Jiyu Wo Oka Suru Kokyo Wo Tsuiho Saretara, Mao No Ohizamoto De Chozetsu Koka No Magic Item Zukuri Hodai Ni Narimashita 4 (Kadokawa Books) [Light Novel]

[Machine Translation] When Princess Liana visits the border to defeat a new type of magical beast, she is reunited with her sister, who has been revitalized by Thor's invention. On the other hand, she herself is still contemplating the "Robot Vacuum Cleaner," an item that could clean up the demonic beasts. Elte, niece of Prime Minister Kelv, comes to supervise the invention to make sure that it does not cause any confusion. She suggests that they collect ideas from the public, and the most dangerous golem is born! While Thor's invention surprises Erte and Liana, the Demon King's Domain cooperates with Sophia and finally comes to a direct confrontation with the forces of the empire!

新種の魔獣討伐を名目として国境を訪れたリアナ皇女が再会したのは、トールの発明で活力を得た姉だった。一方当の本人は、魔獣を掃討しうるアイテム、「ロボット掃除機」について思案中。そこへ、トンデモ発明が混乱を齎さないか、監督のため宰相ケルヴの姪・エルテが訪れる。彼女の提案で広く皆からアイディアを募ると、最凶のゴーレムが誕生!?トールの発明がエルテやリアナを驚かせつつも、魔王領はソフィアと協力し、遂に帝国の勢力と直接対決へ!!