Keep your back straight and stay strong

In T city, the Kamiyama Mansion was burned to the ground due to the multiple blasts.

According to the survivors, strange men clad in black appeared that night. There was a battle between the guards and the assassins. People from both sides died. Suddenly, palm-sized drones floated inside the mansion. There were multiple blasts in the blink of an eye. When they realized what was going on, they ran outside the mansion. Grandmother Kamiyama was killed by one of the assassins when she ran upstairs to save her grandson. They found several charred bodies that couldn't be identified. It all happened within 10 minutes.

Kamiyama Takeshi is stumped. In one night, everything changed.

Last night, he ran to find his sister-in-law. When he saw the assassin throwing the blade at her, he pushed her aside. He doesn't remember anything except hearing her scream. Did the assassin get her?