Become Stronger as You Die is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Die, revive, and grow stronger. The story of the "immortal" soldier. "Revive, Human" Shinogami Ai, the weakest recruit in the United Galactic Army, was supposed to have died on the battlefield. However, the chest pierced by the Kaiki, humanity's enemy, has healed, and the torn arm has reattached itself. On the verge of death, Ai made a contract with Nosferatu, the king of the Kaiki, to coexist with him inside his body. Through this contract, Ai can revive even after dying multiple times, and his physical abilities continue to enhance as he becomes one with Nosferatu. Ai always returns alone from battles where his entire unit is wiped out, earning him the nickname "Grim Reaper" and inspiring fear in others. Yet, Ai continues to stand up against the Kaiki for humanity's sake, no matter how many times he dies.