In a world where there is a small number of witches but their magical powers are not so great, my little sister is a one-in-a-million exception who can utilize all kinds of spells! But because of it, my sister now becomes a exploitative (in terms of using magic) brat who always teases me for not having magic capabilities... However, what would happen when she actually runs out of MP (magical power)?

It is evident to see that the author (Tsujishima Moto) utilized a lot of the ideas in this oneshot in his serialization of "The Genius Witch Lost MP."