My Demon Cry Baby, Maria

An earnest little demon ends up in dire straits as he's summoned by a human with a libido rivaling that of a devil.

A college student Satoru Shiiyama had a crush on Jun Mariya ever since middle school, but the object of his affections dies in an accident. In the midst of his grieving, Satoru accidentally summons a demon and gets a once-in-a-lifetime offer: "In return for your life span, I'll grant you a wish." Having lost all hope, Satoru agrees. Just what is the wish that he made...?

This is a heart-warming(?) love story between a selfish, lustful guy and an honest, cute little demon.

(Source: Renta!)

Note: Also includes 3 chapters of Mariya-kun to Shinigami-chan (毬谷くんと死神さん).