After an accident sent her family to their deaths in the ocean, Hinako Yaotose keeps returning to the thought of sinking forever into the sea herself. With Miko Yashiro as her only friend, Hinako manages to keep up a semi-happy facade, but whenever Miko leaves her side, she slips into despair. Everything changes one summer when she meets a mysterious girl with eyes as deep and clear as the sea, drawing Hinako in like nothing else has in a long time. During her absent-minded search for the girl, Hinako is suddenly pulled underwater by a beastly deep-sea creature, only to awaken to the presence of the girl—Shiori Oumi—who takes on a monstrous form and kills Hinako's attacker. Despite this heroic act, Shiori's intentions are no different from any other monster's: she wants to eat Hinako. The following morning, Shiori walks into Hinako's class as a transfer student, and Hinako cannot help but smile—at last, someone who could fulfill her quiet wish for death has appeared before her.

Oda Akira is the kind of guy who people forget is even there. His unassuming nature pays off, though, when his entire class is swept away to a fantasy world, and he slips easily into his new role as a silent assassin. Between his suspiciously high starting stats and too many details that don't fit, Akira is sure something is wrong. But digging into royal secrets is a dangerous game, and when Akira uncovers an evil scheme, he also makes a powerful enemy—the very king who brought him to this world! With the help of the elven spirit medium Amelia, can he find the power to set things right, and get his revenge?

A decade ago, princess Krystal Novaty “Hime” Nokanatika traveled from another world to escape assassination attempts by an evil force. When she arrives in modern-day Japan, she encounters Haruto Satou. With him she shares a promise: he must forget what he has just witnessed, and the two will become friends. Now heading back to the Nokanatika Kingdom to fulfill her royal duties, Hime bids farewell to Haruto. However, when the young man suddenly remembers his first meeting with Hime, he rushes to the location where she first appeared and crosses the dimensional portal to be reunited with her. His arrival disrupts the marriage ceremony between Krystal and prince Marmarugias Gisaras. The wedding is brutally interrupted by the attack of an abyss monster who threatens the princess' life. Acting impulsively, Hime decides to exchange rings with Haruto, which grants her new husband light powers that permit him to slay the monster. Now dubbed as the Ring King, Haruto must marry four other princesses to acquire new magical powers and have a chance to prevail in his fight against the enemy of the world: the Abyss King.

students of Daikoku Welfare Academy—a boarding school where they are educated, protected, and monitored—the mythical Santa Claus is a forgotten character of fiction. For the adults, Santa Claus is a very real menace that needs to be neutralized by the Saint Nick Pursuit Unit in case he makes an appearance. Shiori Fuyumura, a student of Daikoku Welfare Academy, is determined to find her best friend, Ichie Ono, who has been declared dead after being missing for six months. One morning, Fuyumura summons her fellow class representative, Kazushige Sanda, only to attack the unknowing boy. She is convinced that Sanda is the descendant of the infamous Santa Claus—the only person who can make her wish of finding Ono come true—and is determined to force out his dormant true self by any means necessary.