The Underground Mutation

Li Qinghe smiled and said, 

"However, this pen is only a D-grade xenogeneic. It's not very dangerous. It was first found in an education institution in Nanming city. A tutor used this pen as usual, but that day, the pen carved words in his stomach. It was a blessing in disguise that it was not life-threatening. After that, the pen was kept by the local night watchman and escorted to the headquarters."

"D-grade xenogeneic? Are there many levels of xenogeneics?"

Lu Yuan was a little curious.