@Lily-Garden "I sold my life for ten thousand yen per year" (三日間の幸福, Mikkakan no kōfuku) is a Japanese novel written by Sugaru Miaki and illustrated by E9L. It was published by ASCII Media Works in December 2013. The novel received a manga adaptation titled I Sold My Life for Ten Thousand Yen Per Year (寿命を買い取ってもらった。一年につき、一万円で。, Jumyō o Kaitotte Moratta. Ichinen ni Tsuki, Ichimanen de.) illustrated by Shōichi Taguchi and published by Shueisha on their Shōnen Jump+ platform, and then released in three tankōbon volumes.
(source; Wikipedia)
I have not read the novel myself, but I have read the manga and have to admit I really enjoyed it. Although it was only 16 chapters (a later chapter was added as 16.5) I thought it was a bitter-sweet story that ended up showing how 3 days could actually end up being the best out of 30 years in a lifetime.