Question: how not to summon demon lord?
Answer: How Not to Summon a Demon Lord (Japanese: 異世界魔王と召喚少女の奴隷魔術, Hepburn: Isekai Maō to Shōkan Shōjo no Dorei Majutsu, transl. "The Other World Demon Lord and the Summoning Girl's Slave Magic") is a Japanese light novel series written by Yukiya Murasaki and illustrated by Takahiro Tsurusaki.