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 Hoshi no Samidare and Ashita Dorobou feature everyday life of the male lead taking a turn for the weird. In both cases this involves an extraordinary girl who has plans to change the world and a huge object floating above earth. If you liked one of those two series the other one should prove interesting too.
P.S. This may sound like the plot of a generic series, but those two are far from being generic.
Ishiyama High is home to a whole host of delinquents, including Oga, a legendary badass who's downright devilish. One day Oga finds a man floating down a river, after which the man splits open to reveal a baby inside – but it’s no ordinary baby! The cute tot is actually Beelzebub, the future king of the demons! And as Oga is as mean as they come, Beelzebub latches on to its newfound 'father', much to the other demons' dismay. Now, in addition to battling rival gangs and becoming the strongest delinquent around, Oga must buy diapers, comfort and carry around an annoying baby who's more of a devil than he is!
In both stories main character is slightly evil guy (vicious deliquent in Beelzebub and scheming guy who can pull any cheap tricks to achieve his goal in Hoshi no Samidare). That "protagonist" is suddenly given a role, where the fate of the world is in his hands (being a parent to demon lord ni Beelzebub, and becoming one of the knights that are suppose to protect the planet in Hoshi no Samdare).
Both mangas are filled with comedy mixed with some battle manga elements. Both are walking a fine line between good and evil ( it's hard to decide on what sides are the characters, since they are pretty likable and do good deeds now and then, while still taking actions that may end in world destruction).
Lastly in both mangas demon lord make an appearance as one of the main characters.
In both Hoshi no Samidare and Fate/Stay Night, semi-random people are chosen to take part in a "game" upon which the fate of the world resides. In Fate\Stay Night those people are battling each other and using warriors assigned to them for that purpose. On the other hand in Hoshi no Samider the assigned companions are useless in battle (most of the time) and the people participating in the game have to fight themselves. Also in Hoshi no Samidare they team up to win rather than go agains each other. If you thought that the "game" theme was interesting in one of those manga, you might want to give the other one a try.
Yuki has isolated himself from his high school student life; even his cell phone reflects his detachment, since it only contains information about his surroundings. In his fantasies Yuki is chosen by his friend Deux Ex Machina to participate in a survival game of twelve people, each with a clairvoyant personal diary. The remaining survivor will become the new Lord of Time and Space. However, Yuki wakes from his fantasy to find that his dreams have become reality; his diary now has entries from the future about his surroundings, and he learns that his classmate Yuno is also participating. Even worse, Yuki finds an entry for his imminent Dead End. To stay alive he becomes Yuno's partner, but her diary only contains what will happen to her beloved Yuki. Yuno swears to protect Yuki and uphold her unwavering love for him; she will protect their bond, no matter who she has to get rid of.
While at first glance these two manga may not seem to have a lot in common, they actually have a very similar feel.
They both involve a relatively large group of charcters that are given a special power in order to achieve a specific goal. If you pay attention, you can see that these manga both really deal with how people think and act in certain situations and how things that happened in their past have contributed to the way their personalities are in the present.
Finally, I must also metion in short that they are both seinen and they both have very strong lead female characters.
This one is hard to explain, but Hoshi no Samidare and Ga-rei feel somewhat alike. Maybe it's because of the similarity between the protagonists in those two manga or maybe it's because of the style of humor. Anyway if you liked one of those manga, you probably going to like the other one as well.