Dating sim master Keima Katsuragi wants nothing more than to immerse himself in the 2D world, chasing digital girlfriends. But when the so-called 'Capturing God' answers a mysterious email from an unknown sender, Keima finds himself chasing down real-life ladies in an attempt to help the peppy demon Elsie de Lute Irma capture 'lost souls' escaped from the depths of hell. Now, lest the explosive collar around his neck detonate, Keima must convince various girls to fall in love with him in order to scare out the souls hiding in their hearts.
Otakus helping out girls that attend their respective schools with their problems, be it truancy, personal, conflicts with school regulations or in TWGOK's case, inner demons and stuff. That are personal problems. They have the same brand of comedy and the romance in TWGOK is more prominent than Denpa Kyoushi but they share the same wave length and the other is recommended for readers of either one.
Hikari Hamura, nicknamed Picasso by his peers, always has a pencil and sketchbook in hand. Though he used to spend most of his time with his only friend Chiaki by the river's edge, things changed for the boy forever when a helicopter crashed on top of them, killing Chiaki and leaving him virtually unscathed. Upon awakening, Hikari is told by Chiaki's spirit that he is alive because she prayed for his safety, and in return, he must help classmates in need with the power of his sketchbook, or his body will rot away. Now, with the help of his angelic partner and his artistic skills, Hikari must help save his fellow students, gaining plenty of friends along the way.
Both mangas involve the main character who has to help people with their problems or he will die. And the main character in both mangas are fairly similar, they're also both social outcasts. If you like one you should read the other.
Yuuhi Amamiya is a loner whose mistrust of people was instilled in him at a young age by his abusive grandfather. So when an annoying talking lizard tells the university student that he is one of twelve knights chosen to stop the gigantic "biscuit hammer" before it smashes the Earth to smithereens, Yuuhi has no inclination to rescue such an unkind world. Despite his apathy, the boy is targeted by a golem while going about his day-to-day life, and ends up teaming up with the other knights anyway. One of his new companions is Samidare Asahina, the "princess" and leader of the knights, who secretly is only trying to protect the Earth so she can destroy it herself! Entranced, Yuuhi swears eternal loyalty to this cheerful devil that promises to crush the world he despises.
Both are very good comedy mangas, that are drenched in absurd. In both titles main character is anti-social, sceptical guy, who is suddenly pulled into saving the world stuff. Being put in a cliche situations, they act in unexpected way.
Both titles have some sort of devil playing one of the main characters. In Kami no mizo shiru sekai it's a clumsy helper from hell, that is contracted to main protagonist. In Hoshi no Samidare it's the princess who wants to save the world, just to destroy it later by herself (It is uncertain if she really is the devil, but at many occasions Yuuhi call her devil or demon lord ).
Tomoko Kuroki is eager to begin her new, glamorous, and romantic high school life where she’ll surely become popular and have all the guys vying for her affections. Her plan is sure to succeed, having prepared vigorously by already dating 100 guys... who happen to be video game characters! But when months pass and she can’t seem to get anyone’s attention, let alone talk to them due to her crippling social anxiety, Tomoko’s grandiose dreams turn to shambles! Will she ever be able to have a normal school life?
I don't know about others, but I think these two series share a lot of similarities. They are both about a Student who is unpopular and has spent most of their time playing Dating Games. One is forced to try and make girls love him and just wants to be alone while the other is triyng their hardest to get a boyfriend and doesn't want to be alone. I think if you enjoyed one of these series you should at least give the other a try.