Overwhelming Rage

Along with the help of Kingslayer, Ryuga was able to push the zombies from the railing and they fell on the bottom floor along with the door. 

They did it. Their efforts finally paid off. They felt like they could lose their consciousness now but Ryuga immediately left. He went to the room Sumi was in. Kingslayer also followed him.

Both of them got inside the room and saw something they never expected they would see in their life.

Sumi sat beside the corpse of the zombie, covered in blood while holding a statue in her hands. 

She killed someone for the first time in her entire life. 

Ryuga's eyes widened as he saw Sumi in that state. He was frozen in fear seeing Sumi like that. 

Even though Sumi was safe, they felt like they couldn't make it in time. They could have avoided something this horrible to happen with Sumi if they were just a little bit early.

Ryuga regretted this. He regretted that he wasn't able to come to Sumi's help early.