Watashitachi, Ketsukon Shimashita Fuguu na Ouji to Tensai Majutsushi wa, Inochi no Unmei Kyoudoutai

Ortos, the first prince born of a concubine whose life is being threatened, and Elini, a genius at developing magical artifacts. Elini shielded Ortos from the attackers, but now both of them have fallen into a "soul-bound" state, unable to be more than four steps apart—?!.