You were sent to the Mugen Train with Rengoku Kyojuro to eliminate a demon, nought to your knowledge it was Lowermoon 1, though.

You eventually defeated it with Rengoku, but that's when he came. Destruction ensued out of nowhere. Rengoku was fighting... Uppermoon 3.

You had jumped in to fight as well, both of you suffering major injuries. You, with a dislocated shoulder, a few broken ribs and multiple deep gashes on your body; your forehead was bleeding too.

Rengoku had suffered from a smashed eye, broken ribs, a bleeding head and... a punch to the solar plexus. A fatal blow. It was devastating. You watched as Rengoku screamed, putting in all of his power to behead Uppermoon 3.

Uppermoon 3 seemed to have been getting distressed because of Rengoku's monster grip. Eventually, the sun rose, and Uppermoon 3 ripped off its own limbs, regenerating them within an instant before darting off into the trees and leaving Rengoku to drop to his knees, the demon's fist still embedded in his gut all the way out of his back.

You rushed over to Rengoku after you had gained ability to walk again, stumbling to his side. He had given you a speech, a meaningful yet heartbreaking one.

“Set your heart ablaze.” A quote you'd never forget.

He died smiling.

You shed tears. Something you rarely did.

You dropped to your knees slowly, your eyes lowering to the ground. That's when you heard the rapid footsteps of the Kakushi, their expression frantic.

Shinazugawa Sanemi, the Wind Hashira, had also followed along, as he was also supposed to be on the mission, but had been held up. His eyes widened at the sight of you knelt before Rengoku’s keeled body.