Episodes 5.5 and 13.

Best friends Yuu, Haru, and Kotona enjoy a tranquil high school life together. One day, however, a suspicious man pursues and stabs Kotona—a catastrophe that Yuu and Haru fail to prevent. While hastily carrying the girl to the hospital, the two boys are nearly hit by a truck but miraculously remain unharmed. Instead, they find themselves in a fairy-tale-like kingdom with an exotic diversity of people and wonderful creatures.

To their surprise, the boys discover that Yuu, who has been confined to a wheelchair since childhood, can now walk! Yet they have no time to ponder the puzzling situation, as their friend is gone. Setting off to find Kotona, Yuu and Haru stop at a local pub to inquire about her. But upon inspecting a picture of Asha, the kingdom's princess, the two have a shocking revelation.

Narrating an extraordinary adventure in a magical world, Ni no Kuni demonstrates the special connection between two separate yet parallel worlds and its manifestation of the bonds between individuals.

[Written by MAL Rewrite]

Bonus specials released together with the OVA.

Tensai Bakabon is the tale of a child prodigy and his "philosophical" father. Bakabon‘s father has his own philosophy and he leaves no stone unturned in his quest for answers. Despite his ability to trouble Trouble, for some reason, Papa Bakabon is regarded as "The Great Philosopher," and is sought after for advice, which of course ends up in disastrous results. Tensai Bakabon joins his father in his philosophical quests which drives the people in their town crazy. (Source: Animation Xpress)