宅男写了篇故事，求各位大大指点

谁是后悔药？

SUMMARY: “Form the contract with me, and I shall help you to rewrite a past.” Kikuchi Kurin, a high school girl who lost her parents 6 years ago, met a Death Angel, who offered her a contract. What was his objective? What was he hiding?

Dead

The sky was dead grey.

“Tsk!” the raven teen cursed silently as he dashed in the forest. Sheets of rain beat onto his lanky body mercilessly. His long, dark cape was drenched and weighing him down, making it difficult to move. His black boots were covered in mud as they slapped against the squishy, muddy ground.

Aah, that’s why I hate rain.

The teen thought to himself bitterly as he clutched his armless left shoulder tightly, trying to stop the bleeding. But that was not the only wound he had; blood was gushing out from the centre of his chest, dyeing his dark cape black. “Huff…huff…” he panted painfully as he struggled to keep running, and left a bloody trail behind. His badly injured body finally gave in after running for so long and dropped onto his knees.

This is bad…I’ve lost more blood than I thought.

谁是后悔药？

His vision blurred; those crimson pink eyes of his went hazy. Soon, the raven was not able to stay balanced and collapsed onto the wet, muddy ground. The rain was still pouring down like thick, silver threads. The blood oozing out of his body diffused in the ripples of rain and formed a strange looking web. He blinked tiredly. He knew that he was going to die, since no one will be there to save him. Despite this situation, he smiled faintly.
…Forgive me…
“…”
His lips parted, but no words came out.

谁是后悔药？

Then world became dark and silent.
“Hehehehe…hehehe!”
But the silence was soon broken by a young mocking voice. “Heh, Looks like you need to ‘travel’ again! How lame, you didn’t even last fifteen years this time! Hahaha!”
His body felt heavy. “Crucible?” he opened his eyes sleepily, raising his right arm which felt as heavy as stone after realising he was somehow laying on his back. The teen and a shadow named ‘Crucible’ were in a dark and cold place. There seemed to be no light source but somehow they could see the glassy checkered floor beneath them.
“It took you 3.5 seconds to recognise me, looks like I need to find a replacement for your brain too! Hahaha, what do you think?” The pink eye boy looked as bored as ever. “Aww damn, show some emotion, you stupid human!” Crucible sounded like some spoilt brat who was demanding for sweets. But the teen laid there like a stone, showing no sign of anger.
“…”
“You’re no fun!”
“…Is that all you can say after your master ‘came back’”
‘Humph! My master isn’t  you~ my master is the great Death~ my master simply ordered me to assist you and be your assistant temporarily, and that doesn’t make you my master!” Crucible talked back drawlingly.
“Whatever,” the teen replied emotionlessly. Just like a robot, Crucible thought, and Death knows how long I’m going to be stuck with him.  The ‘robot’ began to rise and sat up, “Speaking of replacement,” he asked as he stared at the creature hiding in the shadow blankly, “Why didn’t you came and teleport me away? Then, I would be able to recover my left arm to fight…”
“Huh~? I don’t think you are any close to winning even with your left arm. And I won’t have enough time to find a replacement anyway.”

谁是后悔药？

“Then why didn’t you say so earlier?” the teen’s voice deepen with threat, “I won’t have to waste another life away if I knew I had no chance of winning.”
“Eh? So you are blaming me for pushing yourself too hard? Can’t you yourself tell that you are losing and should retreat?” Crucible spoke pompously and quickly added, “Oh, by the way, you didn’t ask, and so I didn’t answer.”
The teen lowered his head and muttered some curses quietly and emotionlessly. Crucible was soon amused. The creature even laughed heartily when the teen swore the ‘friendly’ phrases beginning with the letter ‘F’. “Aw, come on! All you have to do is to wait for a few years, which not even closed long compared to your age!” The raven continued staring at the floor as Crucible did his best to ‘cheer’ him up.
“How many years will it take for me to get back my memories and power the next time?” the teen asked sulkily and looked at the horizontal line before him which separates the checkered floor and the empty black space.
“Death knows, I suppose it won’t take more than five years the next time.”
There was a minute of silence before the teen spoke again. “What about her?”
“So you still remember… don’t worry, the next ‘inspection’ is coming soon, and by then we will know whether it’s time to free her or not.”
Crucible was not really sure if he had heard a soft and depressing “Oh…”
How many years was it already? 1257 or 1258?