The story begins when intervenes to save a girl from a massive monster, only to be fatally impaled through the chest. However, the girl, Tokiko Tsumura , is actually an Alchemist Warrior. To save his life, she replaces his heart with a Kakugane —an alchemical device that not only restores his life but also allows him to manifest a unique weapon known as a Buso Renkin .

The terms in your query (, Streaming , Download , Subtitle Indo ) indicate that you are likely looking for Indonesian-subtitled versions of this classic series. Sites like Oploverz and Animeindo have historically been popular hubs for the Indonesian anime community to access such content. If you'd like, I can help you with: Detailed character profiles for Kazuki or Tokiko. A summary of the different types of Buso Renkin weapons. Recommendations for similar supernatural battle anime .

The specific plot point mentioned—high school student being killed one night while trying to save a mysterious girl—is the inciting incident of that story. Series Overview: Buso Renkin