I Became the Girl's Guardian Spirit

He has no name or surname, codenamed Thirteen. With a body of innate sword bones and an exquisite heart with seven orifices, he was adopted by the temple and raised in an inhuman way, known as a "soldier"! No relatives, no friends, no teachers; killing gods, killing Buddhas, killing the king of hell, just a killing machine without any emotions. But one day, an altar appeared in front of him... He was briefly projected into another world, and the person who summoned him was a cute little girl who claimed to be from the earth and traveled to this alien world based on guardian spirits. "Brother, don't leave! Take me with you! Make a contract with me and become my guardian spirit!" "I'm a systematic person! The system is awesome. As long as the binding is successful, there will be a novice gift package." "Bless the guardian spirit with the true damage talent, true damage without time and space restrictions! It is also effective in your original world!" "Do you understand the real damage? Ignore defense! It's amazing!" She thought Thirteen agreed because of the blessing, but in fact he was just too boring. Under the influence of this silly spiritual master, he got a name, and gradually transformed from a cold killing machine into a human being... God Lord: "Thirteen, what are you doing!" He didn't answer, just slashed out with his sword...