Ousama Ranking: Treasure Chest of Courage

Ousama Ranking: Treasure Chest of Courage (王様ランキング 勇気の宝箱, Ōsama Rankingu: Yūki no Takarabako) is a Japanese anime special based on the manga of the same name by Sousuke Tooka. It's billed as a special episode of the Ousama Ranking anime, depicting a new adventure with Bojji and Kage.

The special was announced on August 8, 2022, via the official Ousama Ranking anime Twitter, and is scheduled to air on Fuji TV's Noitamina programming block on April 13, 2023.

Plot
"A treasure chest of unspoken courage is opened."

The special is described as a collection of shorts, showing past instances of courage and personal growth by the cast of Ousama Ranking. Several of these shorts appear to be based on bonus chapters of the Ousama Ranking manga, which are often used to give background information, lore, and updates to various storylines in the manga.

A teaser trailer, released December 4, 2022, shows new footage from the special interspersed with footage from the series. Though intentionally obscure with actual plot details, the teaser shows the following:

A second teaser trailer, released March 19, 2023, appears to show completely original footage, and features the following:
 * Bojji undergoing some kind of rapier training.
 * Hilling and Anne having an adventure together.
 * A flashback to Desha's revolution in the Underworld (which appears to be adapted from the Volume 9 bonus chapter, "Immortality")
 * Bojji traveling with a mysterious figure in gold and blue plate armor.
 * Numerous flashbacks to Kage's childhood with his mother in the Bo Kingdom.
 * A flashback to Bebin's past as a guardsman of the Bosse Kingdom (which appears to be adapted from the Volume 3 bonus chapter, "Those Who Smile Will Be Blessed With Good Fortune And Happiness")
 * Bojji speaking with a reformed Miranjo and King Daida, suggesting the special is a direct sequel to the events of the Ousama Ranking anime, rather than a prequel or interquel.

The tagline for the special appears to be, "I'm sure you'll find it."

Staff

 * Director: Yousuke Hatta
 * Series Composition: Taku Kishimoto
 * Character Design: Atsuko Nozaki
 * Music: Mayuko
 * Animation Work: WIT Studio

Cast

 * Minami Hinata as Bojji
 * Ayumu Murase as Kage
 * Yuuki Kaji as Daida
 * Rina Satou as Hilling
 * Takuya Eguchi as Domas
 * Youji Ueda as Bebin
 * Hiroki Yasumoto as Apeas
 * Hinata Tadokoro as Dorshe
 * Daiki Yamashita as Hokuro
 * Takahiro Sakurai as Despa