Kaito Daimon would be a completely average high school student except for one thing: he's a 'demon' at solving puzzles. Kaito is so brilliant, in fact, that when he's asked to take some 'special' tests of his unique ability, he immediately suspects that the test itself is a test. Kaito suddenly finds himself caught up in a lethal Philosopher's Puzzle made by the sinister group POG, a murderous maze of trap upon trap, where failing to solve the secret correctly will result in death! Fortunately, Kaito's skills prove up to the first test, both for himself and his childhood friend Nanoha, who is also caught up in the deadly scheme. But now that he has been designated as a Solver, he is pulled into a new life where he must travel the world with other Solvers, attempting to solve the latest deadly riddles left by POG. There's a new conundrum around every corner and each deception could lead to death, but once a riddle has been posed, you can count on Kaito to unfold, unravel and unlock it! (Source: Sentai Filmworks)

Kirino Kousaka embodies the ideal student with equally entrancing looks. Her grades are near perfect, and to cover her personal expenses, she works as a professional model alongside her best friend Ayase Aragaki, who abhors liars and all things otaku. But what Ayase doesn't know is that Kirino harbors a deep, entrenched secret that will soon be brought to light. At home one day, Kyousuke, Kirino's perfectly average brother, stumbles upon an erotic game that belongs to none other than his seemingly flawless little sister. With her reputation at stake, Kirino places a gag order on her sibling while simultaneously introducing him to the world of eroge and anime. Through Kirino, Kyousuke encounters the gothic lolita Ruri Gokou and the bespectacled otaku Saori Makishima, thus jump-starting an entirely new lifestyle. But as he becomes more and more involved in his little sister's secret life, it becomes that much harder to keep under wraps. [Written by MAL Rewrite]

Akira Yuki has spent years honing his Bajiquan skills under the guidance of his grandfather. He yearns to see the constellation of the eight stars of heaven, which are only revealed to those with real strength. This burning desire urges him to embark on travels, so as to learn more about how to see the stars. Meanwhile, a nefarious robotics scientist, Eva Durix, desires to create the perfect soldier. Eva's group, Judgment 6, tracks down and kidnaps Sarah Bryant, a college student and close acquaintance of Akira who is investigating a mysterious accident concerning her brother. Akira must now fight his way to Sarah to save her from the clutches of Judgement 6, a perilous path sure to be paved with countless challenges.

Tooru Kouno's attractive appearance draws unexpected attention on his first day at an all-boys school. Having to transfer to a school without girls has been bad enough, but adding to his list of frustrations are boys staring at him all day long. However, he hopes that there may be girls around, since he ran into a lovely pink-haired girl on campus earlier that day. After being escorted to his dorm by his classmate, Yuujirou Shihoudani, he meets a student named Mikoto Yutaka, who looks eerily similar to the girl he saw previously. To his shock, he realizes Mikoto is the girl and confronts him about this revelation. Yuujirou divulges that he and Mikoto crossdress as part of their job: a school tradition in which attractive first years are chosen as idols called "Princesses" in order to boost the morale of the students—and because of his looks, Tooru has been chosen by the student council as their third Princess!