|Hataraku Maou-sama! Light Novel Volume 12|
|Release Date||February 10, 2015|
|Number of Pages||344|
|Cover Character/s||Sadao Maou, Emi Yusa, Lailah|
|Previous Novel||Light Novel Volume 11|
|Next Novel||Light Novel Volume 13|
Hataraku Maou-sama! Light Novel Volume 12 (はたらく魔王さま！12) is the 12th book of the Hataraku Maou-sama! Light Novel series.
Meanwhile, Emi has disappeared from her home and Nord and Lailah are unable to find her. Through Rika, Chiho find Emi at Maki's home. Maki was a former colleague of Emi when she worked at Docodemo. After talking to Emi and some conversation later, Emi decides to return home. She had calmed down after staying at Maki's home for two days. On the trip back home through the subway, the train was attacked by an unknown shadow. Unwilling to use her full power to avoid trouble with normal humans and distracted by the appearance of Amane, Esmeranda and her mother, Emi almost suffered heavy injuries. Having withstood the heavy attack of the shadow for Emi, Lailah fell into unconciousness. Maou came and healed Lailah with his demonic magic, only to rush back to work right after. After a battle with Amane, the shadow escaped. Emi, in a state of denial after being protected by Lailah, rejected too see her mother and waited for Maou to come home in room 201. To find out more about the incident through Maou as Emi was in no state to hold a conversation, Suzuno came to Mcronald, only to find Rika and Acies there as well. Maou explained what he knew to them and returned to work. Based on what he said and the situation, Suzuno hinted at Maou cared for Emi a lot, only to have Rika misunderstood it as Maou having feelings for Emi. Acies found the talk amusing and told the conversation to Maou, which in turn rage at the idea. On his way home, he was accompanied by Gabriel, who acted as a guard through Shiba Miki's order. Gabriel manages to make Maou express his honest thoughts, which is overheard by Emilia. With Maou's confession and realization of being protected by him many times before, Emi finally accepted her feelings and embraced Maou.
A few days after that, the delivery service finally came into business, with Emi managing the phone. Emi's attitude towards Maou changed as well, with him as the only one who could understand and willing to protect her. Finishing their work, Emi wanted to go home together with Maou as they received the same email to from an unknown number to return. It was from Shiba Miki, who wanted them to hear out Lailah's story as the situation had deteriorated. They found out that the shadow was actually Iron who had gone missing after the battle with 3 angels in Ente Isla. Lailah overhead what Maou said the night the attack happened as well, so she changed her approach and offer Emi and Maou a contract. Using this, Maou created a situation where Emi would have to face Lailah directly without his help. The side effect of that decision made Emi stay by his side practically all the time after that, inviting Chiho's jealousy and many people to gather at the Demon Fortress, greatly distressing Maou,