Happy World!

Tragedy struck Kotaro Higuchi as a child in the form of his mother's death in a car accident. But fate has a funny way of doing things, and years after the fact an angel-in-training named Misha decides to pay him a visit. Joined by his fellow elementary school students, and later by the nicest demon you'll ever meet, Kotaro and Misha will embark on a journey of laughs and love.

In the present, the Japanese government has been conducting experiments to genetically engineer a human: a girl named Rizel. The experiment was a success -- sort of. While healthy and cheerful, 12-year-old Rizel also ended up possessing the uncanny need for “love” to further her development, as well as tears which were in fact volitile explosives! When sadness can end up destroying a city block, what's a girl to do except... get married?! For Iwari Tomori, the young man chosen as the most appropriate partner for Rizel, life is about to change, for better or for worse!

Goro Mutsumi is a young man with that never seems to catch a break; he has a hard time keeping a job, has horrible luck, and continuously finds himself in bad circumstances.  However, things change one day when he comes home - having been fired yet again - and finds three young girls sitting in his apartment. They're the reincarnated angels of his deceased pets, and they're here to turn his luck around given how well he treated them in their past lives. While the idea sounds like a godsend, things don't go quite according to plan; the angels tend to cause more harm than good, and twelve altogether end up joining Goro's cramped household! In addition to learning how to co-exist with his newly acquired roommates, Goro must also defend them and himself against four sacred beasts who are after him for mysterious reasons. One thing's for certain: Goro's life will never be the same!