Eternal Bonds Beyond Time: His World [Final Reupload]

After the death of a friend, you vowed to take revenge against the demon king. You were chosen as his Tsuguko, seeing how close both your breathing styles were. You trained hard to reach one of the few top ranks to see yourself slowly fall in love with a cold and aloof boy.

Rewritten of 'My and your parallel world' note: The plot is different(slightly)! And fixed many grammatical errors.