Perfectly Imperfect

Humans would rather shower their love on pets than have kids. As a result, the residents of the underworld cannot reincarnate as humans. To get out of the underworld, some spirits resort to anything, including reincarnating as cats and dogs instead. Some are lucky enough to be reborn as human but are cursed with an ill-fated life. How will they change the hand that fate has dealt them and go on to live a good life?