Kazuki is the worst magician in a school for the gifted, and three girls want him anyway, not because he's secretly powerful, because his bloodline is genetically rare. The show takes that absurd premise and makes you actually care about which girl understands him versus which ones see him as a prize to win. Comedy carries it, romance grounds it, the ecchi doesn't apologize for itself, and somehow a kid with 32 spell casts for his entire life becomes someone worth rooting for.
Kazuki Shikimori has the worst luck of any student at Aoi Academy, a prestigious school where elite magicians hone their craft. Every spell a mage casts counts against a personal limit, and exceed that number and you literally turn to dust. Kazuki's limit is pathetically low compared to his peers, making him the school's biggest underachiever. Then three gorgeous girls suddenly appear in his life: Yuuna, Kuriko, and Rin, each with their own agenda. There's just one problem. They're not interested in Kazuki himself. They want his genes, believing his bloodline holds valuable magical potential. As Kazuki gets pulled deeper into their schemes, he finds himself constantly using magic to help them out of dangerous situations. Each spell brings him closer to his limit, each act of heroism another step toward oblivion. Now he's caught between his desire to protect the girls and his instinct for self-preservation, watching his spell count tick down with every choice he makes.