Embryo

Some women possess dormant seeds known as embryos linked to supernatural beings. These remain inactive until triggered by a strong shock, causing them to erupt and summon dangerous creatures. Narusawa Yu has the ability to control and extract these transformed embryos. His younger sister, Mikoto, uses the embryo within her to manifest a sword for battling the summoned entities and also monitors her lecherous brother. As embryos begin to emerge unexpectedly at their school, the siblings believe a deliberate effort is being made on campus to provoke their mutations.