I am going to use My Body Swap Ability to gather Harem

I, Makoto Tanuki, was just your ordinary student until one day, I was suddenly blessed with a system. However, the system required me to make love with my childhood friend or they will take the system away. With that as a motivation and my bodyswap ability granted by the system, I shall strive to train my childhood friend into my sex slave! She will become a sex crazed slut only for me! — Description from novelcodex.org