When high schooler Tsuguna passes away prematurely due to a divine error, a god promises him a favor in his next life. Reincarnated into a noble family in a magical realm, Tsuguna wields a unique ability to summon creatures, a gift he specifically requested. However, his cursed appearance and delayed manifestation of powers isolate him in a gloomy basement, engrossed in his family's ancient texts. Through a pivotal discovery, Tsuguna unlocks his latent potential and embarks on a journey with his summoned ally to enhance his magical prowess.