Peace Pet Rental's Lag is a robotic dog. He can be pretty slow at times and can't perform tasks aside from those written in his program, but despite all this, he's everyone's favorite dog. Soon, however, he is tackling people's problems in ways not included in his program, and it seems almost miraculous... Something mysterious has awakened within his heart even though he's supposed to be a machine with no emotions. What is Lag's true nature? For those lost in despair and sorrow and those with wounded hearts comes this healing tale of love, kindness, and sacrifice. (Source: DMG)

Tenshi no Shinzou was digitally published in English as Angel Heart by Digital Manga Publishing on July 26, 2012.