Not Midori's lore, just the overall system of angels and devils. (IF YOU LIKE READING, PREPARE TO READ 😎)

Four gods, also known as the Divine Four, were created by The Source. The source has created multiple gods, along with other heavens and hells (More or so, ones from other religious views.) The heaven in Midori no Mondai has four rulers, including three of the Divine Four. Kami, God himself, Kaze, God of Elements, Taiyo, God of Light, and Seijin, Kami's wife. There are certain angels who go down to earth and find ways to benefit mortals. These angels are known as Seraphims. For example, we have Cerul, the angel of love, basically MNM's cupid. (More Seraphim info: https://grid-paint.com/images/details/6640bec929a34501ab82976f0f9c2bbd)

Mortals can also go against things Seraphims provide them, which is extremely rare.

As you know, Akuma, the fourth of the divine four, has seven children, AKA the Seven Deadly sins. Kami too has Seven children, these are the Seven Heavenly Virtues (Basically the opposite of chaos lords) There are two other systems of Angels, the Saints and the Guardians. The guardians are angels that work under Seraphims, their role is to help the seraphim do their job, or be a guardian angel to a specific mortal. Saints on the other hand are just souls who have been sent to heaven (That is, if The Decider says they've had Kami's judgement) After one has died, the Seraphim named Death will give that soul three options. They can go to the Upper Gate and be given judgement from The Decider, Stay on Earth as a ghost, or be reincarnated into a new body, which can place you into a different decade or time period as well. (Forgetting your past life, along with your decision to be reincarnated)

The underworld however, only has two rulers. Akuma, the Devil, and Iro, his wife. They have things similar to Seraphims, ones who spread negative emotions and malice. These are what one would simply call a demon. An example would be Kuro, the fallen angel of Heartbreak. (It's more complicated than that but yk) The children of Akuma, The Seven Deadly sins, are few of the most feared demons, and can wander around the human world freely as long as they have an anchor. For example, Ikari, or Chaos as you know him, is free to go wherever he pleases as long as Midori, his anchor, stays alive. Once an anchor dies, the Chaos or Peace lord will be sent back to their immortal home. As mentioned before, These Sins have opposites, the Virtues (Which is ironic how they're supposed to hate each other, even though they're cousins, It's gonna be one hell of an in law family if Midori ends up marrying Yokubo, The sin of Lust 😭😭😭😭) The sinners are given Akuma's judgement, and they get to stay in hell as long as they play along with their given ordeals. The Hellish Ordeals can alter a Sinner's immortal living condition, like Kushu, a man who's currently the MNM version of the Mangle because he chose the ordeal of wrath. There are eight ordeals currently. Each ordeal involving a deadly sin, the eighth involved being Akuma's servant. The ordeal with the best low injury rate is that of sloth, just don't awaken Taida and you're fine. Choose the ordeal of wrath and you're as good as done. If you decline all the ordeals, you will be wiped of existence, with nothing after....