Second season of Kekkon Yubiwa Monogatari.

The daily life of high school student Naoto Watari revolves around his little sister Suzushiro. As their parents passed away two years prior, the siblings have been passed from one relative to another, resulting in Naoto taking the most responsibility for her. Although things have not been easy for the two, Naoto is now content with living at their aunt's place. This newfound peace is suddenly turned on its head when Satsuki Tachibana enrolls at Naoto's school. The two used to be good friends, but after Satsuki completely destroyed his family's garden, she disappeared from Naoto's life. Despite what happened, Satsuki seems to be making advances toward Naoto now that they have reconnected. Coupled with other people around him that harbor secrets, Naoto's desire for an idyllic life may be at jeopardy.

A 20-year-old shut-in is suddenly transported from his apartment, only to appear in front of a goddess who offers him a second chance at life. Although she grants him overpowered magical abilities in this new world, when he awakes as the newborn Prince Reinhardt, his talents are only measured at Level 2. Thinking their child to be an abysmal failure, his royal parents abandon him in the woods. There, the prince, who names himself Haruto, encounters Flay, a Flame Fenrir who decides to devote her life in service to him. Haruto's relative, Gold Zenfis, meets them both in the woods and decides to adopt the child as his own. Nine years pass with Haruto under the care of the Zenfis family. His mastery over his overpowered barrier magic increases by the day, though Haruto would rather not use it to help others. He practices his magic in secret, preferring to have his family believe that he is weak. However, his younger sister, Charlotte, discovers his strength, and with the assistance of Flay, Haruto protects her and the rest of the Zenfis family from harm. With a shifty plot stirring in the kingdom, Haruto only wishes to stay inside and watch anime, but it seems he will have to use his magic to keep the family that took him in safe.

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.