Redeem: Tatta Hitotsu no Eien

Chiaki and Kuon are on cloud nine and couldn't be happier. As the two are walking home after a date, a car suddenly comes speeding down the road and hits Kuon, leaving him dying in Chiaki's arms. As Chiaki begs the heavens to save his lover, he's unexpectedly whisked back 10 years! With this new start, Chiaki is determined to keep Kuon safe from harm, but Kuon wants nothing to do with him! But is there a reason the universe chose to send him to this point in time?

(Source: Tapas, edited)