BAOH THE VISITOR

A secret organization called "Doress" has funded the development of a genetically engineered parasite code-named "BAOH." Organisms infected by BAOH become living survival machines, virtually indestructible, able to mutate their body structure to meet any threat. Properly controlled, the BAOH parasite could allow Doress to control the World. Unfortunately, their first human guinea-pig, a young man named Hashizawa Ikuroo, has managed to escape, along with a young girl, Sumire, who has a strange precognitive gift. Unless Doress operatives can find and destroy Ikuroo before the BAOH parasite fully manifests, their evil dream will come to naught. But BAOH, comfortably hiding in Ikuroo's brain, won't make it easy. (Source: AnimEigo) — Description from AniList community (anilist.co).